Fix AstGraphBuilder for loops like for(;;).

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/control-builders.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node-properties.h"
@@ skipping 592 matching lines @@
 
 
 void AstGraphBuilder::VisitForStatement(ForStatement* stmt) {
   LoopBuilder for_loop(this);
   VisitIfNotNull(stmt->init());
   for_loop.BeginLoop();
   if (stmt->cond() != NULL) {
     VisitForTest(stmt->cond());
     Node* condition = environment()->Pop();
     for_loop.BreakUnless(condition);
+  } else {
+    for_loop.BreakUnless(jsgraph()->TrueConstant());
   }
   VisitIterationBody(stmt, &for_loop, 0);
   for_loop.EndBody();
   VisitIfNotNull(stmt->next());
   for_loop.EndLoop();
 }
 
 
 // TODO(dcarney): this is a big function.  Try to clean up some.
 void AstGraphBuilder::VisitForInStatement(ForInStatement* stmt) {
@@ skipping 1493 matching lines @@
     DCHECK(NodeProperties::GetFrameStateInput(node)->opcode() ==
            IrOpcode::kDead);
     NodeProperties::ReplaceFrameStateInput(
         node, environment()->Checkpoint(ast_id, combine));
   }
 }
 
 }
 }
 }  // namespace v8::internal::compiler