Fix for a possible bug in RegExp stack guard.

src/x64/regexp-macro-assembler-x64.cc

Index: src/x64/regexp-macro-assembler-x64.cc
diff --git a/src/x64/regexp-macro-assembler-x64.cc b/src/x64/regexp-macro-assembler-x64.cc
index 7f804477f3a405609bea79237c806bb0675cf6f2..a782bd7052c0fc866709b58b3fd33b292a028338 100644
--- a/src/x64/regexp-macro-assembler-x64.cc
+++ b/src/x64/regexp-macro-assembler-x64.cc
@@ -1185,7 +1185,7 @@ int RegExpMacroAssemblerX64::CheckStackGuardState(Address* return_address,
   MaybeObject* result = Execution::HandleStackGuardInterrupt();
 
   if (*code_handle != re_code) {  // Return address no longer valid
-    intptr_t delta = *code_handle - re_code;
+    intptr_t delta = code_handle->address() - re_code->address();
     // Overwrite the return address on the stack.
     *return_address += delta;
   }