fix(compile): Interpolate @ locals before the link function runs

Do a one-off interpolation of @ locals to ensure that the link fn receives attributes that are already interpolated.

src/ng/compile.js

@@ -735,9 +735,13 @@ function $CompileProvider($provide) {
                   scope[scopeName] = value;
                 });
                 attrs.$$observers[attrName].$$scope = parentScope;
+                if( attrs[attrName] ) {
+                  // If the attribute has been provided then we trigger an interpolation to ensure the value is there for use in the link fn
+                  scope[scopeName] = $interpolate(attrs[attrName])(parentScope);
+                }
                 break;
               }
-
+              
               case '=': {
                 parentGet = $parse(attrs[attrName]);
                 parentSet = parentGet.assign || function() {

test/ng/compileSpec.js

@@ -1812,27 +1812,21 @@ describe('$compile', function() {
     describe('attribute', function() {
       it('should copy simple attribute', inject(function() {
         compile('<div><span my-component attr="some text">');
-        expect(componentScope.attr).toEqual(undefined);
-        expect(componentScope.attrAlias).toEqual(undefined);
-
-        $rootScope.$apply();
 
         expect(componentScope.attr).toEqual('some text');
         expect(componentScope.attrAlias).toEqual('some text');
         expect(componentScope.attrAlias).toEqual(componentScope.attr);
       }));
 
-
-      it('should update when interpolated attribute updates', inject(function() {
-        compile('<div><span my-component attr="hello {{name}}">');
-        expect(componentScope.attr).toEqual(undefined);
-        expect(componentScope.attrAlias).toEqual(undefined);
-
+      it('should set up the interpolation before it reaches the link function', inject(function() {
         $rootScope.name = 'misko';
-        $rootScope.$apply();
-
+        compile('<div><span my-component attr="hello {{name}}">');
         expect(componentScope.attr).toEqual('hello misko');
         expect(componentScope.attrAlias).toEqual('hello misko');
+      }));
+
+      it('should update when interpolated attribute updates', inject(function() {
+        compile('<div><span my-component attr="hello {{name}}">');
 
         $rootScope.name = 'igor';
         $rootScope.$apply();