fix(duplicate): fix#1081, load patch should also check the duplicate flag (#1121)

Author: JiaLiPassion

lib/zone.ts

@@ -643,6 +643,7 @@ const Zone: ZoneType = (function(global: any) {
 performance&&performance['measure']&&performance['measure'](name,label);
 }
 mark('Zone');
+constcheckDuplicate=global[('__zone_symbol__forceDuplicateZoneCheck')]===true;
 if(global['Zone']){
 // if global['Zone'] already exists (maybe zone.js was already loaded or
 // some other lib also registered a global object named Zone), we may need
@@ -653,8 +654,7 @@ const Zone: ZoneType = (function(global: any) {
 // but when user load page2 again, error occurs because global['Zone'] already exists.
 // so we add a flag to let user choose whether to throw this error or not.
 // By default, if existing Zone is from zone.js, we will not throw the error.
-if(global[('__zone_symbol__forceDuplicateZoneCheck')]===true||
-typeofglobal['Zone'].__symbol__!=='function'){
+if(checkDuplicate||typeofglobal['Zone'].__symbol__!=='function'){
 thrownewError('Zone already loaded.');
 }else{
 returnglobal['Zone'];
@@ -693,7 +693,9 @@ const Zone: ZoneType = (function(global: any) {
 
 static__load_patch(name: string,fn: _PatchFn): void{
 if(patches.hasOwnProperty(name)){
-throwError('Already loaded patch: '+name);
+if(checkDuplicate){
+throwError('Already loaded patch: '+name);
+}
 }elseif(!global['__Zone_disable_'+name]){
 constperfName='Zone:'+name;
 mark(perfName);
@@ -1364,4 +1366,4 @@ const Zone: ZoneType = (function(global: any) {
 
 performanceMeasure('Zone','Zone');
 returnglobal['Zone']=Zone;
-})(typeofwindow!=='undefined'&&window||typeofself!=='undefined'&&self||global);
+})(typeofwindow!=='undefined'&&window||typeofself!=='undefined'&&self||global);