Remove the fcontext field from all contexts.

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index ce07333bb9531c7547a7fb9eb3ebb3fcdb8dd985..a80821f82c4f840b94ba1421df1ac723dd551f71 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -1766,14 +1766,17 @@ void MacroAssembler::LoadContext(Register dst, int context_chain_length) {
     mov(dst, esi);
   }
 
-  // We should not have found a 'with' context by walking the context chain
-  // (i.e., the static scope chain and runtime context chain do not agree).
-  // A variable occurring in such a scope should have slot type LOOKUP and
-  // not CONTEXT.
+  // We should not have found a with or catch context by walking the context
+  // chain (i.e., the static scope chain and runtime context chain do not
+  // agree).  A variable occurring in such a scope should have slot type
+  // LOOKUP and not CONTEXT.
   if (emit_debug_code()) {
-    cmp(dst, Operand(dst, Context::SlotOffset(Context::FCONTEXT_INDEX)));
-    Check(equal, "Yo dawg, I heard you liked function contexts "
-                 "so I put function contexts in all your contexts");
+    cmp(FieldOperand(dst, HeapObject::kMapOffset),
+        isolate()->factory()->with_context_map());
+    Check(not_equal, "Variable resolved to with context.");
+    cmp(FieldOperand(dst, HeapObject::kMapOffset),
+        isolate()->factory()->with_context_map());
+    Check(not_equal, "Variable resolved to catch context.");
   }
 }