Fast codegen: Implement with.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index ca0c98926770fb8d8cdec574917d1f0b56309adf..2c055a32929df7bb6a1c864ad709fb31d568efeb 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -703,12 +703,12 @@ void CodeGenSelector::VisitReturnStatement(ReturnStatement* stmt) {
 
 
 void CodeGenSelector::VisitWithEnterStatement(WithEnterStatement* stmt) {
-  BAILOUT("WithEnterStatement");
+  ProcessExpression(stmt->expression(), Expression::kValue);
 }
 
 
 void CodeGenSelector::VisitWithExitStatement(WithExitStatement* stmt) {
-  BAILOUT("WithExitStatement");
+  // Supported.
 }