Unify logic of stack trace generation for extension errors

extensions/renderer/module_system.cc

Index: extensions/renderer/module_system.cc
diff --git a/extensions/renderer/module_system.cc b/extensions/renderer/module_system.cc
index 1f337643476d06ad230eab1fb4949e61ec616a8f..f9e8d91df590065a82a31cf5725ab0aa320c1049 100644
--- a/extensions/renderer/module_system.cc
+++ b/extensions/renderer/module_system.cc
@@ -552,7 +552,11 @@ v8::Handle<v8::String> ModuleSystem::WrapSource(v8::Handle<v8::String> source) {
       "(function(define, require, requireNative, requireAsync, exports, "
       "console, privates,"
       "$Array, $Function, $JSON, $Object, $RegExp, $String) {"
-      "'use strict';");
+      "'use strict';"
+      // Prevent extensions from overriding the Error constructor.
+      // Use window.Error instead of $Error to make sure that extensions can
+      // still use "instanceof Error" for exception handling.
+      "var Error = window.Error;");
   v8::Handle<v8::String> right = v8::String::NewFromUtf8(GetIsolate(), "\n})");
   return handle_scope.Escape(v8::Local<v8::String>(
       v8::String::Concat(left, v8::String::Concat(source, right))));