[Isolates] Less TLS reads in parser and full codegens.

src/full-codegen.h

Index: src/full-codegen.h
diff --git a/src/full-codegen.h b/src/full-codegen.h
index 8d9fe2d3322f7cd57f5c91395debf5cb965e342f..33fd60e232d3f6c63884a337bfbd47a5320d4dac 100644
--- a/src/full-codegen.h
+++ b/src/full-codegen.h
@@ -74,7 +74,8 @@ class FullCodeGenerator: public AstVisitor {
   };
 
   explicit FullCodeGenerator(MacroAssembler* masm)
-      : masm_(masm),
+      : isolate_(Isolate::Current()),
+        masm_(masm),
         info_(NULL),
         nesting_stack_(NULL),
         loop_depth_(0),
@@ -516,6 +517,7 @@ class FullCodeGenerator: public AstVisitor {
     loop_depth_--;
   }
 
+  Isolate* isolate() { return isolate_; }
   MacroAssembler* masm() { return masm_; }
 
   class ExpressionContext;
@@ -567,6 +569,8 @@ class FullCodeGenerator: public AstVisitor {
       codegen_->set_new_context(old_);
     }
 
+    Isolate* isolate() const { return codegen_->isolate(); }
+
     // Convert constant control flow (true or false) to the result expected for
     // this expression context.
     virtual void Plug(bool flag) const = 0;
@@ -743,6 +747,7 @@ class FullCodeGenerator: public AstVisitor {
     virtual bool IsEffect() const { return true; }
   };
 
+  Isolate* isolate_;
   MacroAssembler* masm_;
   CompilationInfo* info_;
   Label return_label_;