[WIP] Initial CallFunctionCallback builtin.

src/arm/macro-assembler-arm.h

Index: src/arm/macro-assembler-arm.h
diff --git a/src/arm/macro-assembler-arm.h b/src/arm/macro-assembler-arm.h
index efa84995221f4e684034f1c5e103916d69a571be..b8ec437303e265bf3bae09ab7b15de27accb5d22 100644
--- a/src/arm/macro-assembler-arm.h
+++ b/src/arm/macro-assembler-arm.h
@@ -1231,6 +1231,9 @@ class MacroAssembler: public Assembler {
   // via --debug-code.
   void AssertUndefinedOrAllocationSite(Register object, Register scratch);
 
+  // Abort if argument is not a valid API call result, enabled via --debug-code.
+  void AssertApiCallResult(Register object);
+
   // Abort execution if reg is not the root value with the given index,
   // enabled via --debug-code.
   void AssertIsRoot(Register reg, Heap::RootListIndex index);