feat($compile): add partialDigest property in directive definition

A directive asking for a child or isolated scope can now ask
for that scope to have partialDigest, making any digest triggered
from inside the directive only do dirty-checking for that scope
and its descendants.

Author: rodyhaddad

src/ng/compile.js

@@ -954,7 +954,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
 
           if (nodeLinkFn) {
             if (nodeLinkFn.scope) {
-              childScope = scope.$new();
+              childScope = scope.$new(false, nodeLinkFn.partialDigest);
               $node.data('$scope', childScope);
             } else {
               childScope = scope;
@@ -1368,6 +1368,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
       }
 
       nodeLinkFn.scope = newScopeDirective && newScopeDirective.scope === true;
+      nodeLinkFn.partialDigest = nodeLinkFn.scope && newScopeDirective.partialDigest;
       nodeLinkFn.transcludeOnThisElement = hasTranscludeDirective;
       nodeLinkFn.templateOnThisElement = hasTemplate;
       nodeLinkFn.transclude = childTranscludeFn;
@@ -1448,7 +1449,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
           var LOCAL_REGEXP = /^\s*([@=&])(\??)\s*(\w*)\s*$/;
           var $linkNode = jqLite(linkNode);
 
-          isolateScope = scope.$new(true);
+          isolateScope = scope.$new(true, newIsolateScopeDirective.partialDigest);
 
           if (templateDirective && (templateDirective === newIsolateScopeDirective ||
               templateDirective === newIsolateScopeDirective.$$originalDirective)) {

test/ng/compileSpec.js

@@ -2167,6 +2167,42 @@ describe('$compile', function() {
         });
       });
     });
+
+    describe('partialDigest', function () {
+
+      beforeEach(module(function() {
+        directive('isolatePartialDigest', valueFn({
+          scope: {},
+          partialDigest: true
+        }));
+        directive('newPartialDigest', valueFn({
+          scope: true,
+          partialDigest: true
+        }));
+      }));
+
+
+      it('should allow you to mark an isolated scope with partialDigest', inject(
+        function($rootScope, $compile) {
+          spyOn($rootScope, '$new').andCallThrough();
+
+          expect($rootScope.$new).not.toHaveBeenCalled();
+
+          element = $compile('<div isolate-partial-digest></div>')($rootScope);
+          expect($rootScope.$new).toHaveBeenCalledWith(true, true);
+        }));
+
+
+      it('should allow you to mark a new scope with partialDigest', inject(
+        function($rootScope, $compile) {
+          spyOn($rootScope, '$new').andCallThrough();
+
+          expect($rootScope.$new).not.toHaveBeenCalled();
+
+          element = $compile('<div new-partial-digest></div>')($rootScope);
+          expect($rootScope.$new).toHaveBeenCalledWith(false, true);
+        }));
+    });
   });