fix($compile): fix missing error handling when new-scope directive is applied before isolated-scope directive

Given dirA, which requests new scope, and dirB, which requests new & isolated scope. If dirA is applied *after* dirB, $compile reports an error ('Multiple directives [dirB, dirA] asking for new/isolated scope'), which is expected. However, if dirA is applied *before* dirB, e.g. because dirA has high priority, then no error is thrown. This is the inconsistency. Plus, dirA ends up sharing the isolated scope created for dirB, which may break dirA because it might need to access to parent scope's members. This fix addresses this situation by throwing error regardless of order of directive application.

Closes angular#4402

Author: buunguyen

src/ng/compile.js

@@ -794,18 +794,19 @@ function $CompileProvider($provide) {
         }
 
         if (directiveValue = directive.scope) {
-          newScopeDirective = newScopeDirective || directive;
-
           // skip the check for directives with async templates, we'll check the derived sync directive when
           // the template arrives
           if (!directive.templateUrl) {
-            assertNoDuplicate('new/isolated scope', newIsolateScopeDirective, directive, $compileNode);
             if (isObject(directiveValue)) {
+              assertNoDuplicate('new/isolated scope', newIsolateScopeDirective || newScopeDirective, directive, $compileNode);
               safeAddClass($compileNode, 'ng-isolate-scope');
               newIsolateScopeDirective = directive;
+            } else {
+              assertNoDuplicate('new/isolated scope', newIsolateScopeDirective, directive, $compileNode);  
             }
             safeAddClass($compileNode, 'ng-scope');
           }
+          newScopeDirective = newScopeDirective || directive;
         }
 
         directiveName = directive.name;

test/ng/compileSpec.js

@@ -1539,6 +1539,25 @@ describe('$compile', function() {
           })
         );
 
+        it('should not allow more than one isolate scope creation per element regardless of directive priority', function() {
+          module(function($compileProvider) {
+            $compileProvider.directive('highPriorityScope', function() {
+              return {
+                restrict: 'C',
+                priority: 1,
+                scope: true,
+                link: function() {}
+              }
+            });
+          }); 
+          inject(function($compile) {
+            expect(function(){
+              $compile('<div class="iscope-a; high-priority-scope"></div>');
+            }).toThrowMinErr('$compile', 'multidir', 'Multiple directives [highPriorityScope, iscopeA] asking for new/isolated scope on: ' +
+                    '<div class="iscope-a; high-priority-scope ng-scope">');
+          });
+        });
+
 
         it('should create new scope even at the root of the template', inject(
           function($rootScope, $compile, log) {