Bug 856243 - Add missing do_QueryFrame support. r=dholbert

layout/generic/nsFrameSetFrame.cpp

@@ -142,6 +142,7 @@ protected:
 class nsHTMLFramesetBlankFrame : public nsLeafFrame
 {
 public:
+  NS_DECL_QUERYFRAME_TARGET(nsHTMLFramesetBlankFrame)
   NS_DECL_FRAMEARENA_HELPERS
 
 #ifdef DEBUG

layout/generic/nsHTMLCanvasFrame.h

@@ -34,6 +34,7 @@ public:
   typedef mozilla::layers::LayerManager LayerManager;
   typedef mozilla::FrameLayerBuilder::ContainerParameters ContainerParameters;
 
+  NS_DECL_QUERYFRAME_TARGET(nsHTMLCanvasFrame)
   NS_DECL_FRAMEARENA_HELPERS
 
   nsHTMLCanvasFrame(nsStyleContext* aContext) : nsContainerFrame(aContext) {}

layout/generic/nsQueryFrame.h

@@ -8,7 +8,8 @@
 #include "nscore.h"
 
 #define NS_DECL_QUERYFRAME_TARGET(classname)                    \
-  static const nsQueryFrame::FrameIID kFrameIID = nsQueryFrame::classname##_id;
+  static const nsQueryFrame::FrameIID kFrameIID = nsQueryFrame::classname##_id; \
+  typedef classname* Has_NS_DECL_QUERYFRAME_TARGET;
 
 #define NS_DECL_QUERYFRAME                                      \
   virtual void* QueryFrame(FrameIID id);
@@ -33,7 +34,7 @@
 #define NS_QUERYFRAME_TAIL_INHERITANCE_ROOT                     \
   default: break;                                               \
   }                                                             \
-  return nullptr;                                                \
+  return nullptr;                                               \
 }
 
 class nsQueryFrame
@@ -63,9 +64,10 @@ public:
 
   template<class Dest>
   operator Dest*() {
-    if (!mRawPtr)
-      return nullptr;
-
+    if (!mRawPtr) {
+      // Ensure that Dest declared itself as a queryframe target.
+      return static_cast<typename Dest::Has_NS_DECL_QUERYFRAME_TARGET>(nullptr);
+    }
     return reinterpret_cast<Dest*>(mRawPtr->QueryFrame(Dest::kFrameIID));
   }