RegExpMacroAssembler::CheckStackGuardState should update input string pointer

src/ia32/regexp-macro-assembler-ia32.cc

Index: src/ia32/regexp-macro-assembler-ia32.cc
diff --git a/src/ia32/regexp-macro-assembler-ia32.cc b/src/ia32/regexp-macro-assembler-ia32.cc
index 8b0b9ab91154520ec34bf35dd9b66cae0a746271..dbf01abff08714d7979578b239b4a93ea5d6a20f 100644
--- a/src/ia32/regexp-macro-assembler-ia32.cc
+++ b/src/ia32/regexp-macro-assembler-ia32.cc
@@ -1141,6 +1141,11 @@ int RegExpMacroAssemblerIA32::CheckStackGuardState(Address* return_address,
     frame_entry<const String*>(re_frame, kInputString) = *subject;
     frame_entry<const byte*>(re_frame, kInputStart) = new_address;
     frame_entry<const byte*>(re_frame, kInputEnd) = new_address + byte_length;
+  } else if (frame_entry<const String*>(re_frame, kInputString) != *subject) {
+    // Subject string might have been a ConsString that underwent
+    // short-circuiting during GC. That will not change start_address but
+    // will change pointer inside the subject handle.
+    frame_entry<const String*>(re_frame, kInputString) = *subject;
   }
 
   return 0;