[SalesForce] I can’t get index of the row in a aura:iteration component in the client side controller

In my lightning component, I have a table with column that has a menu in it. The menu items are for edit and delete. I'm trying to find a way to get the row that was clicked on and so far everything thing I've found/tried hasn't worked. This is in a Summer 16 sandbox w/Locker Service enabled.

These approaches no longer work:

• How to remove items from a dynamic list in Lightning component?
• http://bobbuzzard.blogspot.com/2016/01/freezing-users-with-lightning-components.html

Here is the top level component:

<aura:component implements="flexipage:availableForAllPageTypes,force:appHostable,force:hasRecordId">
<c:AffiliationsList curRecordId="{!v.recordId}" />
<c:AffiliationDetails />

Here is the component that has the datagrid:

<aura:component implements="flexipage:availableForAllPageTypes,force:appHostable" controller="AffiliationController">
<ltng:require styles="/resource/SLDS103/assets/styles/salesforce-lightning-design-system-ltng.min.css"/>

<aura:attribute name="curRecordId" type="String"/>
<aura:attribute name="afList" type="AffiliationWrapper[]"/>
<aura:attribute name="numAf" type="Integer" default="0"/>

<aura:handler name="init" value="{!this}" action="{!c.doInit}"/>
<aura:registerEvent name="appEvent" type="c:affiliationToEdit"/>

<div class="slds">
    <div class="slds-card">
        <div class="slds-card__header slds-grid">
            <div class="slds-media slds-media--center slds-has-flexi-truncate">
                <div class="slds-media__figure">
                    <c:svg class="slds-icon slds-icon-standard-contact slds-icon--small" xlinkHref="/resource/SLDS103/assets/icons/standard-sprite/svg/symbols.svg#contact"/>
                </div>
                <div class="slds-media__body">
                    <h2 class="slds-text-heading--small slds-truncate">Affiliations ({!v.numAf})</h2>
                </div>
            </div>
        </div>
        <div class="slds-card__body">
            <table class="slds-table slds-table--bordered slds-table--striped slds-max-medium-table--stacked-horizontal">
                <thead>
                    <tr class="slds-text-heading--label">
                        <th class="slds-is-sortable" scope="col">
                            <div class="slds-truncate">Relationship
                                <button class="slds-button slds-button--icon-bare">
                                    <c:svg class="slds-button__icon slds-button__icon--small" xlinkHref="/resource/SLDS103/assets/icons/utility-sprite/svg/symbols.svg#arrowdown"/>
                                    <span class="slds-assistive-text">Relationship</span>
                                </button>
                            </div>
                        </th>
                        <th class="slds-is-sortable" scope="col">
                            <div class="slds-truncate">Status
                                <button class="slds-button slds-button--icon-bare">
                                    <c:svg class="slds-button__icon slds-button__icon--small" xlinkHref="/resource/SLDS103/assets/icons/utility-sprite/svg/symbols.svg#arrowdown"/>
                                    <span class="slds-assistive-text">Status</span>
                                </button>
                            </div>
                        </th>
                        <th class="slds-is-sortable" scope="col">
                            <div class="slds-truncate">Project
                                <button class="slds-button slds-button--icon-bare">
                                    <c:svg class="slds-button__icon slds-button__icon--small" xlinkHref="/resource/SLDS103/assets/icons/utility-sprite/svg/symbols.svg#arrowdown"/>
                                    <span class="slds-assistive-text">Project</span>
                                </button>
                            </div>
                        </th>
                        <th class="slds-is-sortable" scope="col">
                            <div class="slds-truncate">Sub-Project
                                <button class="slds-button slds-button--icon-bare">
                                    <c:svg class="slds-button__icon slds-button__icon--small" xlinkHref="/resource/SLDS103/assets/icons/utility-sprite/svg/symbols.svg#arrowdown"/>
                                    <span class="slds-assistive-text">Sub-Project</span>
                                </button>
                            </div>
                        </th>
                        <th class="slds-is-sortable" scope="col">
                            <div class="slds-truncate">Task
                                <button class="slds-button slds-button--icon-bare">
                                    <c:svg class="slds-button__icon slds-button__icon--small" xlinkHref="/resource/SLDS103/assets/icons/utility-sprite/svg/symbols.svg#arrowdown"/>
                                    <span class="slds-assistive-text">Task</span>
                                </button>
                            </div>
                        </th>
                        <th class="slds-is-sortable" scope="col">
                            <div class="slds-truncate">Notes
                                <button class="slds-button slds-button--icon-bare">
                                    <c:svg class="slds-button__icon slds-button__icon--small" xlinkHref="/resource/SLDS103/assets/icons/utility-sprite/svg/symbols.svg#arrowdown"/>
                                    <span class="slds-assistive-text">Notes</span>
                                </button>
                            </div>
                        </th>
                        <th class="slds-cell-shrink"></th>
                    </tr>
                </thead>
                <tbody>
                    <aura:iteration items="{!v.afList}" var="af" indexVar="idx">
                        <tr class="slds-hint-parent slds-has-flexi-truncate" id="{!idx}">
                            <td class="slds-truncate slds-cell-wrap" data-label="Relationship">{!af.relationship}</td>
                            <td class="slds-truncate" data-label="Status">{!af.status}</td>
                            <td class="slds-truncate slds-cell-wrap" data-label="Project">
                                <a >{!af.project}</a>
                            </td>
                            <td class="slds-truncate slds-cell-wrap" data-label="Sub-Project">{!af.subProject}</td>
                            <td class="slds-truncate slds-cell-wrap" data-label="Task">{!af.task}</td>
                            <td class="slds-truncate slds-cell-wrap" data-label="Notes">{!af.note}</td>
                            <td class="slds-cell-shrink" data-label="Actions">
                                <ui:button aura:id="edit" label="Edit" press="{!c.editAffiliation}"/>
                                <!-- <ui:menu>
                                    <ui:menuTriggerLink aura:id="trigger" title="more"/>
                                    <ui:menuList class="actionMenu" aura:id="actionMenu">
                                        <ui:actionMenuItem aura:id="edit" label="Edit" click="{!c.editAffiliation}"/>
                                        <ui:actionMenuItem aura:id="delete" label="Delete" click="{!c.deleteAffiliation}"/>
                                    </ui:menuList>
                                </ui:menu> -->
                            </td>
                        </tr>
                    </aura:iteration>
                </tbody>
            </table>
        </div>
    </div>
</div>

Here is the controller:

({
    doInit : function(component, event, helper) {
        helper.loadAffiliations(component, event);
    },
    editAffiliation : function(component, event, helper) {
        helper.editRecord(component, event);
    }
})

Here is the helper:

({
    loadAffiliations : function(cmp, ev) {
        var action = cmp.get("c.getAffiliations");
        action.setParams({
            "currentId": cmp.get("v.curRecordId")
        });
        action.setCallback(this, function(response) {
            var state = response.getState();
            if(state === "SUCCESS") {
                var affiliations = response.getReturnValue();
                cmp.set('v.numAf', affiliations.length);
                cmp.set('v.afList', affiliations);
            }
            else if (state === "ERROR") {
                console.log('errors', response.getError());
            }
        });
        $A.enqueueAction(action);
    },
    editRecord : function(cmp, ev) {
        var row = cmp.getEvent("editAffiliation");
        console.log('row', row);
    }
})

console.log('row', row); logs out as null.

Originally my approach was just to pull the indexVar and then I'd be set but that's when I started finding out that none of the old ways worked anymore.

In my function, I'm thinking I should be able to get the value via getSource() on the event, but so far I haven't been able to figure out what, if any, key holds that value. It seems there should be a way to get to the dataset. Is there anyway to get the value for data-index from the event? It appears that the Locker Service has blocked everything. Or is there another approach that would work better? Any suggestions?