[stubs] Split ToNumberStub into reusable subparts.

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 87f0ea9677d97d34c2c2324ab757b5615c9eca5b..a4cf3d72e90409cebad8cc0f5f579d80687197cd 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -959,6 +959,15 @@ void MacroAssembler::AssertNumber(Register object) {
   }
 }
 
+void MacroAssembler::AssertNotNumber(Register object) {
+  if (emit_debug_code()) {
+    test(object, Immediate(kSmiTagMask));
+    Check(not_equal, kOperandIsANumber);
+    cmp(FieldOperand(object, HeapObject::kMapOffset),
+        isolate()->factory()->heap_number_map());
+    Check(not_equal, kOperandIsANumber);
+  }
+}
 
 void MacroAssembler::AssertSmi(Register object) {
   if (emit_debug_code()) {