Fix mac x64 build.

src/x64/fast-codegen-x64.cc

Index: src/x64/fast-codegen-x64.cc
diff --git a/src/x64/fast-codegen-x64.cc b/src/x64/fast-codegen-x64.cc
index ba22135725a7032099ec7af232fdf841c00719ce..6c96ad60afc5659adfce64a563cafb7aa3d611d6 100644
--- a/src/x64/fast-codegen-x64.cc
+++ b/src/x64/fast-codegen-x64.cc
@@ -1678,8 +1678,7 @@ Register FastCodeGenerator::context_register() { return rsi; }
 
 
 void FastCodeGenerator::StoreToFrameField(int frame_offset, Register value) {
-  ASSERT_EQ(POINTER_SIZE_ALIGN(frame_offset),
-            static_cast<intptr_t>(frame_offset));
+  ASSERT_EQ(POINTER_SIZE_ALIGN(frame_offset), static_cast<int>(frame_offset));
   __ movq(Operand(rbp, frame_offset), value);
 }