[WIP] Initial CallFunctionCallback builtin.

src/arm/code-stubs-arm.cc

Index: src/arm/code-stubs-arm.cc
diff --git a/src/arm/code-stubs-arm.cc b/src/arm/code-stubs-arm.cc
index fc59f4007e1589f75e219534a55db84a1eb6f8af..6b0298941068bf4a982f6d65f8055e2b98b1860c 100644
--- a/src/arm/code-stubs-arm.cc
+++ b/src/arm/code-stubs-arm.cc
@@ -2613,11 +2613,6 @@ void InternalArrayConstructorStub::Generate(MacroAssembler* masm) {
   GenerateCase(masm, FAST_ELEMENTS);
 }
 
-static int AddressOffset(ExternalReference ref0, ExternalReference ref1) {
-  return ref0.address() - ref1.address();
-}
-
-
 // Calls an API function.  Allocates HandleScope, extracts returned value
 // from handle and propagates exceptions.  Restores context.  stack_space
 // - space to be unwound on exit (includes the call JS arguments space and
@@ -2732,6 +2727,9 @@ static void CallApiFunctionAndReturn(MacroAssembler* masm,
   __ cmp(r4, r5);
   __ b(ne, &promote_scheduled_exception);
 
+  // Check if the function returned a valid JavaScript value.
+  __ AssertApiCallResult(r0);
+
   __ mov(pc, lr);
 
   // Re-throw by promoting a scheduled exception.
@@ -2810,6 +2808,12 @@ void CallApiCallbackStub::Generate(MacroAssembler* masm) {
   // holder
   __ push(holder);
 
+  if (!is_store()) {
+    __ mov(r0, Operand(argc()));
+    __ Jump(masm->isolate()->builtins()->CallFunctionCallback(),
+            RelocInfo::CODE_TARGET);
+  }
+
   // Prepare arguments.
   __ mov(scratch, sp);