remove most uses of Isolate::Current in arch specific files

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 7d9e2f70527f6994470aa53a96dfce3c90a4c851..d371c456c1a21d53f08b065a5da787aa2879dde6 100644
--- a/src/ia32/regexp-macro-assembler-ia32.cc
+++ b/src/ia32/regexp-macro-assembler-ia32.cc
@@ -1099,7 +1099,6 @@ int RegExpMacroAssemblerIA32::CheckStackGuardState(Address* return_address,
                                                    Code* re_code,
                                                    Address re_frame) {
   Isolate* isolate = frame_entry<Isolate*>(re_frame, kIsolate);
-  ASSERT(isolate == Isolate::Current());
   if (isolate->stack_guard()->IsStackOverflow()) {
     isolate->StackOverflow();
     return EXCEPTION;