Oilpan: move WebDevToolsFrontend to the heap.

Source/web/WebLocalFrameImpl.cpp

Index: Source/web/WebLocalFrameImpl.cpp
diff --git a/Source/web/WebLocalFrameImpl.cpp b/Source/web/WebLocalFrameImpl.cpp
index 7513df6512234c0a8a410bab4abd01a89ebbe46d..cc9d28775eb275c5af227330f02bf5bec240d237 100644
--- a/Source/web/WebLocalFrameImpl.cpp
+++ b/Source/web/WebLocalFrameImpl.cpp
@@ -214,6 +214,7 @@
 #include "web/TextFinder.h"
 #include "web/WebDataSourceImpl.h"
 #include "web/WebDevToolsAgentImpl.h"
+#include "web/WebDevToolsFrontendImpl.h"
 #include "web/WebFrameWidgetImpl.h"
 #include "web/WebPluginContainerImpl.h"
 #include "web/WebRemoteFrameImpl.h"
@@ -1559,7 +1560,7 @@ WebLocalFrameImpl::WebLocalFrameImpl(WebFrameClient* client)
     , m_inputEventsScaleFactorForEmulation(1)
     , m_userMediaClientImpl(this)
     , m_geolocationClientProxy(GeolocationClientProxy::create(client ? client->geolocationClient() : 0))
-    , m_webDevToolsFrontend(0)
+    , m_webDevToolsFrontend(nullptr)
 #if ENABLE(OILPAN)
     , m_selfKeepAlive(this)
 #endif
@@ -1585,6 +1586,7 @@ DEFINE_TRACE(WebLocalFrameImpl)
     visitor->trace(m_textFinder);
     visitor->trace(m_printContext);
     visitor->trace(m_geolocationClientProxy);
+    visitor->trace(m_webDevToolsFrontend);
     visitor->template registerWeakMembers<WebFrame, &WebFrame::clearWeakFrames>(this);
     WebFrame::traceFrames(visitor, this);
 }