refactor(language-server): Ensure language service is enabled in angular repo

The language service disables if it cannot find angular core in the
project files. This updates the lookup to work for the angular/angular repo which
runs against the uncompiled sources.

Author: atscott

server/src/session.ts

@@ -1367,7 +1367,10 @@ function isExternalAngularCore(path: string): boolean {
 }
 
 function isInternalAngularCore(path: string): boolean {
-  return path.endsWith('angular2/rc/packages/core/index.d.ts');
+  // path in g3
+  return path.endsWith('angular2/rc/packages/core/index.d.ts') || 
+  // angular/angular repository direct sources
+  path.indexOf('angular/packages/core/src') !== -1;
 }
 
 function isTypeScriptFile(path: string): boolean {