Fix win64 build by using int instead of size_t for position in StringBuilder

Review URL: http://codereview.chromium.org/6353002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6313 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x64/lithium-codegen-x64.cc

@@ -83,7 +83,7 @@ void LCodeGen::Comment(const char* format, ...) {
 
   // Copy the string before recording it in the assembler to avoid
   // issues when the stack allocated buffer goes out of scope.
-  size_t length = builder.position();
+  int length = builder.position();
   Vector<char> copy = Vector<char>::New(length + 1);
   memcpy(copy.start(), builder.Finalize(), copy.length());
   masm()->RecordComment(copy.start());