[es7] implement |do| expressions proposal

src/compiler/ast-graph-builder.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/ast-graph-builder.h"
 
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/js-type-feedback.h"
@@ skipping 1639 matching lines @@
   }
   ast_context()->ProduceValue(literal);
 }
 
 
 void AstGraphBuilder::VisitNativeFunctionLiteral(NativeFunctionLiteral* expr) {
   UNREACHABLE();
 }
 
 
+void AstGraphBuilder::VisitDoExpression(DoExpression* expr) {
+  VisitBlock(expr->block());
+  VisitVariableProxy(expr->result());
+}
+
+
 void AstGraphBuilder::VisitConditional(Conditional* expr) {
   IfBuilder compare_if(this);
   VisitForTest(expr->condition());
   Node* condition = environment()->Pop();
   compare_if.If(condition);
   compare_if.Then();
   Visit(expr->then_expression());
   compare_if.Else();
   Visit(expr->else_expression());
   compare_if.End();
@@ skipping 2618 matching lines @@
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8