Change the representation of catch contexts.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index 8b0c83367ea23cf089c766a6919fd12a0b38ad9e..521b4765176817f3c196f0c723b668a303cf8f57 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -648,7 +648,8 @@ class Heap {
 
   // Allocate a catch context.
   MUST_USE_RESULT MaybeObject* AllocateCatchContext(Context* previous,
-                                                    JSObject* extension);
+                                                    String* name,
+                                                    Object* thrown_object);
   // Allocate a 'with' context.
   MUST_USE_RESULT MaybeObject* AllocateWithContext(Context* previous,
                                                    JSObject* extension);