Bug 1001157. Assert that there is no exception pending on the JSContext afer a DOM call if the call was not marked as throwing or if it did not throw on the ErrorResult. r=peterv

dom/bindings/Codegen.py

@@ -5580,6 +5580,8 @@ class CGCallGenerator(CGThing):
             self.cgRoot.append(CGIndenter(errorReport))
             self.cgRoot.append(CGGeneric("}\n"))
 
+        self.cgRoot.append(CGGeneric("MOZ_ASSERT(!JS_IsExceptionPending(cx));\n"))
+
     def define(self):
         return self.cgRoot.define()