DevTools: minor improvements of CodeGenerator code.

result declaration was moved close to the usage:

     TypeBuilder::HeapProfiler::HeapSnapshotObjectId out_heapSnapshotObjectId;

-    RefPtr<JSONObject> result = JSONObject::create();
     if (protocolErrors->length()) {
         reportProtocolError(&callId, InvalidParams, String::format(InvalidParamsFormatString, commandName(kHeapProfiler_getHeapObjectIdCmd)), protocolErrors);
         return;
     }
     ErrorString error;
+    RefPtr<JSONObject> result = JSONObject::create();
     m_heapProfilerAgent->getHeapObjectId(&error, in_objectId, &out_heapSnapshotObjectId);
     if (!error.length()) {
         result->setString("heapSnapshotObjectId", out_heapSnapshotObjectId);

BUG=

Review URL: https://codereview.chromium.org/326013005

git-svn-id: svn://svn.chromium.org/blink/trunk@175888 bbb929c8-8fbe-4397-9dbb-9b2b20218538