Bug 687458 - TimeStamp in FPSState uninitialized, leads to crash; r=romaxa

gfx/layers/opengl/LayerManagerOGL.h

@@ -499,7 +499,9 @@ private:
         , fps(0)
         , initialized(false)
         , fcount(0)
-      {}
+      {
+        last = TimeStamp::Now();
+      }
       void DrawFPS(GLContext*, CopyProgram*);
   } mFPS;