Refactor ExternalReference::isolate_address() to not rely on Isolate::Current().

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

Index: src/ia32/regexp-macro-assembler-ia32.h
diff --git a/src/ia32/regexp-macro-assembler-ia32.h b/src/ia32/regexp-macro-assembler-ia32.h
index 7aea385863341621a76139f904b8a38f8bcda72d..6040d8058ab5f817f09efc4d726d444aeabbd179 100644
--- a/src/ia32/regexp-macro-assembler-ia32.h
+++ b/src/ia32/regexp-macro-assembler-ia32.h
@@ -30,6 +30,7 @@
 
 #include "ia32/assembler-ia32.h"
 #include "ia32/assembler-ia32-inl.h"
+#include "macro-assembler.h"
 
 namespace v8 {
 namespace internal {
@@ -196,6 +197,8 @@ class RegExpMacroAssemblerIA32: public NativeRegExpMacroAssembler {
   // (ecx) and increments it by a word size.
   inline void Pop(Register target);
 
+  Isolate* isolate() const { return masm_->isolate(); }
+
   MacroAssembler* masm_;
 
   // Which mode to generate code for (ASCII or UC16).