refactor($compile): move $scope.$on('$destroy') handler out of initializeDirectiveBindings

Since only one of three invocations of `initializeDirectiveBindings` actually
adds a `$destroy` handler to the scope (the others just manually call unwatch
as needed), we can move that code out of this method.

This also has the benefit of simplifying what parameters need to be passed
through to the linking functions

Closes #12528

Author: jbedard

src/ng/compile.js

@@ -1437,11 +1437,6 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
             if (nodeLinkFn.scope) {
               childScope = scope.$new();
               compile.$$addScopeInfo(jqLite(node), childScope);
-              var destroyBindings = nodeLinkFn.$$destroyBindings;
-              if (destroyBindings) {
-                nodeLinkFn.$$destroyBindings = null;
-                childScope.$on('$destroyed', destroyBindings);
-              }
             } else {
               childScope = scope;
             }
@@ -1460,8 +1455,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
               childBoundTranscludeFn = null;
             }
 
-            nodeLinkFn(childLinkFn, childScope, node, $rootElement, childBoundTranscludeFn,
-                       nodeLinkFn);
+            nodeLinkFn(childLinkFn, childScope, node, $rootElement, childBoundTranscludeFn);
 
           } else if (childLinkFn) {
             childLinkFn(scope, node.childNodes, undefined, parentBoundTranscludeFn);
@@ -2025,8 +2019,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
         return elementControllers;
       }
 
-      function nodeLinkFn(childLinkFn, scope, linkNode, $rootElement, boundTranscludeFn,
-                          thisLinkFn) {
+      function nodeLinkFn(childLinkFn, scope, linkNode, $rootElement, boundTranscludeFn) {
         var i, ii, linkFn, controller, isolateScope, elementControllers, transcludeFn, $element,
             attrs;
 
@@ -2060,24 +2053,28 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
           compile.$$addScopeClass($element, true);
           isolateScope.$$isolateBindings =
               newIsolateScopeDirective.$$isolateBindings;
-          initializeDirectiveBindings(scope, attrs, isolateScope,
-                                      isolateScope.$$isolateBindings,
-                                      newIsolateScopeDirective, isolateScope);
+          var parentWatchDestroyer = initializeDirectiveBindings(scope, attrs, isolateScope,
+                                        isolateScope.$$isolateBindings,
+                                        newIsolateScopeDirective);
+          if (parentWatchDestroyer) {
+            isolateScope.$on('$destroy', parentWatchDestroyer);
+          }
         }
         if (elementControllers) {
           // Initialize bindToController bindings for new/isolate scopes
           var scopeDirective = newIsolateScopeDirective || newScopeDirective;
           var bindings;
           var controllerForBindings;
+          var destroyBindings;
           if (scopeDirective && elementControllers[scopeDirective.name]) {
             bindings = scopeDirective.$$bindings.bindToController;
             controller = elementControllers[scopeDirective.name];
 
             if (controller && controller.identifier && bindings) {
               controllerForBindings = controller;
-              thisLinkFn.$$destroyBindings =
+              destroyBindings =
                   initializeDirectiveBindings(scope, attrs, controller.instance,
-                                              bindings, scopeDirective);
+                                              bindings, scopeDirective) || noop;
             }
           }
           for (i in elementControllers) {
@@ -2091,8 +2088,8 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
               $element.data('$' + i + 'Controller', controllerResult);
               if (controller === controllerForBindings) {
                 // Remove and re-install bindToController bindings
-                thisLinkFn.$$destroyBindings();
-                thisLinkFn.$$destroyBindings =
+                destroyBindings();
+                destroyBindings =
                   initializeDirectiveBindings(scope, attrs, controllerResult, bindings, scopeDirective);
               }
             }
@@ -2354,7 +2351,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
               childBoundTranscludeFn = boundTranscludeFn;
             }
             afterTemplateNodeLinkFn(afterTemplateChildLinkFn, scope, linkNode, $rootElement,
-              childBoundTranscludeFn, afterTemplateNodeLinkFn);
+              childBoundTranscludeFn);
           }
           linkQueue = null;
         });
@@ -2371,8 +2368,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
           if (afterTemplateNodeLinkFn.transcludeOnThisElement) {
             childBoundTranscludeFn = createBoundTranscludeFn(scope, afterTemplateNodeLinkFn.transclude, boundTranscludeFn);
           }
-          afterTemplateNodeLinkFn(afterTemplateChildLinkFn, scope, node, rootElement, childBoundTranscludeFn,
-                                  afterTemplateNodeLinkFn);
+          afterTemplateNodeLinkFn(afterTemplateChildLinkFn, scope, node, rootElement, childBoundTranscludeFn);
         }
       };
     }
@@ -2632,8 +2628,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
 
     // Set up $watches for isolate scope and controller bindings. This process
     // only occurs for isolate scopes and new scopes with controllerAs.
-    function initializeDirectiveBindings(scope, attrs, destination, bindings,
-                                         directive, newScope) {
+    function initializeDirectiveBindings(scope, attrs, destination, bindings, directive) {
       var onNewScopeDestroyed;
       forEach(bindings, function(definition, scopeName) {
         var attrName = definition.attrName,
@@ -2719,16 +2714,12 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
             break;
         }
       });
-      var destroyBindings = onNewScopeDestroyed ? function destroyBindings() {
+
+      return onNewScopeDestroyed && function destroyBindings() {
         for (var i = 0, ii = onNewScopeDestroyed.length; i < ii; ++i) {
           onNewScopeDestroyed[i]();
         }
-      } : noop;
-      if (newScope && destroyBindings !== noop) {
-        newScope.$on('$destroy', destroyBindings);
-        return noop;
-      }
-      return destroyBindings;
+      };
     }
   }];
 }