Disentangle assembler from isolate.

src/x87/macro-assembler-x87.h

Index: src/x87/macro-assembler-x87.h
diff --git a/src/x87/macro-assembler-x87.h b/src/x87/macro-assembler-x87.h
index 8fe19de6422a861a1cd3334672e16baf439ee475..a3267b52b1ffd2383c2d64a4efff52f5f09a7234 100644
--- a/src/x87/macro-assembler-x87.h
+++ b/src/x87/macro-assembler-x87.h
@@ -60,6 +60,8 @@ class MacroAssembler: public Assembler {
   MacroAssembler(Isolate* isolate, void* buffer, int size,
                  CodeObjectRequired create_code_object);
 
+  Isolate* isolate() const { return isolate_; }
+
   void Load(Register dst, const Operand& src, Representation r);
   void Store(Register src, const Operand& dst, Representation r);
 
@@ -860,6 +862,7 @@ class MacroAssembler: public Assembler {
  private:
   bool generating_stub_;
   bool has_frame_;
+  Isolate* isolate_;
   // This handle will be patched with the code object on installation.
   Handle<Object> code_object_;