Create specialized code stubs for PixelArray loads.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index 1c86817aa81a1ebee155a5095fe47c9a5bff59b2..0eef0ab169b235e6ba9d6699b8198b060776016c 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -177,6 +177,7 @@ namespace internal {
   V(InitializeConstGlobal_symbol, "InitializeConstGlobal")               \
   V(KeyedLoadSpecialized_symbol, "KeyedLoadSpecialized")                 \
   V(KeyedStoreSpecialized_symbol, "KeyedStoreSpecialized")               \
+  V(KeyedLoadPixelArray_symbol, "KeyedLoadPixelArray")                   \
   V(stack_overflow_symbol, "kStackOverflowBoilerplate")                  \
   V(illegal_access_symbol, "illegal access")                             \
   V(out_of_memory_symbol, "out-of-memory")                               \