[builtins] Start refactoring the Apply builtin.

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 25ec35eb2c944771ea65268bac66981bf8f013f4..6750382536dac54826f6a0c871b0a13fc71aae25 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -821,6 +821,16 @@ void MacroAssembler::AssertSmi(Register object) {
   }
 }
 
+void MacroAssembler::AssertFixedArray(Register object) {
+  if (emit_debug_code()) {
+    test(object, Immediate(kSmiTagMask));
+    Check(not_equal, kOperandIsASmiAndNotAFixedArray);
+    Push(object);
+    CmpObjectType(object, FIXED_ARRAY_TYPE, object);
+    Pop(object);
+    Check(equal, kOperandIsNotAFixedArray);
+  }
+}
 
 void MacroAssembler::AssertFunction(Register object) {
   if (emit_debug_code()) {