[BUGFIX release-1-13] Ensure concatenatedProperties are not stomped.

When `_propagateAttrsToThis` is invoked it iterates all properties that
are present in `this.attrs` and calls `this.set(attrName, attrValue)`.
This is normally exactly what you expect. However, in the case of
`concatenatedProperties` and `mergedProperties` this `set`ing causes the
concatenated / merged property to be completely clobbered.

The fix introduced in #12073 adds a very simple work around for the
internally known items (just hard coding things like `classNames`,
`classNameBindings`, `attributeBindings`, and `actions`). This was
obviously a very naive check, and leaves any external usages of
`concatenatedProperties` in components/views completely hosed.

---

The changes here introduces a __avoidPropagating property that we can
use to prevent `concatenatedProperties` and `mergedProperties` from
being set inside `_propagateAttrsToThis`. To avoid introducing this cost
for every component created (when only classes can define new
concatenated / merged properties) we are storing the
`__avoidPropagating` on the constructor itself.

packages/ember-htmlbars/tests/integration/component_invocation_test.js

@@ -799,6 +799,29 @@ QUnit.test('specifying classNames results in correct class', function(assert) {
   ok(button.is('.foo.bar.baz.ember-view'), 'the element has the correct classes: ' + button.attr('class'));
 });
 
+QUnit.test('specifying custom concatenatedProperties avoids clobbering', function(assert) {
+  expect(1);
+
+  let clickyThing;
+  registry.register('component:some-clicky-thing', Component.extend({
+    concatenatedProperties: ['blahzz'],
+    blahzz: ['blark', 'pory'],
+    init() {
+      this._super(...arguments);
+      clickyThing = this;
+    }
+  }));
+
+  view = EmberView.extend({
+    template: compile('{{#some-clicky-thing blahzz="baz"}}Click Me{{/some-clicky-thing}}'),
+    container: container
+  }).create();
+
+  runAppend(view);
+
+  assert.deepEqual(clickyThing.get('blahzz'),  ['blark', 'pory', 'baz'], 'property is properly combined');
+});
+
 // jscs:disable validateIndentation
 if (isEnabled('ember-htmlbars-component-generation')) {
   QUnit.module('component - invocation (angle brackets)', {

packages/ember-views/lib/compat/attrs-proxy.js

@@ -2,6 +2,7 @@ import { Mixin } from 'ember-metal/mixin';
 import { symbol } from 'ember-metal/utils';
 import { PROPERTY_DID_CHANGE } from 'ember-metal/property_events';
 import { on } from 'ember-metal/events';
+import EmptyObject from 'ember-metal/empty_object';
 
 export function deprecation(key) {
   return `You tried to look up an attribute directly on the component. This is deprecated. Use attrs.${key} instead.`;
@@ -13,9 +14,37 @@ function isCell(val) {
   return val && val[MUTABLE_CELL];
 }
 
+function setupAvoidPropagating(instance) {
+  // This caches the list of properties to avoid setting onto the component instance
+  // inside `_propagateAttrsToThis`.  We cache them so that every instantiated component
+  // does not have to pay the calculation penalty.
+  let constructor = instance.constructor;
+  if (!constructor.__avoidPropagating) {
+    constructor.__avoidPropagating = new EmptyObject();
+    let i, l;
+    for (i = 0, l = instance.concatenatedProperties.length; i < l; i++) {
+      let prop = instance.concatenatedProperties[i];
+
+      constructor.__avoidPropagating[prop] = true;
+    }
+
+    for (i = 0, l = instance.mergedProperties.length; i < l; i++) {
+      let prop = instance.mergedProperties[i];
+
+      constructor.__avoidPropagating[prop] = true;
+    }
+  }
+}
+
 let AttrsProxyMixin = {
   attrs: null,
 
+  init() {
+    this._super(...arguments);
+
+    setupAvoidPropagating(this);
+  },
+
   getAttr(key) {
     let attrs = this.attrs;
     if (!attrs) { return; }
@@ -42,14 +71,7 @@ let AttrsProxyMixin = {
     let attrs = this.attrs;
 
     for (let prop in attrs) {
-      if (prop !== 'attrs' &&
-          // These list of properties are concatenated and merged properties of
-          // Ember.View / Ember.Component. Setting them here results in them being
-          // completely stomped and not handled properly, BAIL OUT!
-          prop !== 'actions' &&
-          prop !== 'classNames' &&
-          prop !== 'classNameBindings' &&
-          prop !== 'attributeBindings') {
+      if (prop !== 'attrs' && !this.constructor.__avoidPropagating[prop]) {
         this.set(prop, this.getAttr(prop));
       }
     }