Add support for partial invalidates in WebView

Bug #3461349

This change also fixes two bugs that prevented partial invalidates
from working with other views. Both bugs were in our EGL implementation:
they were preventing the caller from comparing the current context/surface
with another context/surface. This was causing HardwareRenderer to always
redraw the entire screen.

Change-Id: I33e096b304d4a0b7e6c8f92930f71d2ece9bebf5

include/utils/Functor.h

@@ -26,6 +26,7 @@ public:
     Functor() {}
     virtual ~Functor() {}
     virtual status_t operator ()() { return true; }
+    virtual status_t operator ()(float* data, uint32_t len) { return true; }
 };
 
 }; // namespace android