Remove Expression::bounds_, in order to conserve memory during parsing.

src/ast/ast-type-bounds.h

Index: src/ast/ast-type-bounds.h
diff --git a/src/ast/ast-type-bounds.h b/src/ast/ast-type-bounds.h
new file mode 100644
index 0000000000000000000000000000000000000000..ec26fdfc024f7380f0534b9b4ba660b732a47b44
--- /dev/null
+++ b/src/ast/ast-type-bounds.h
@@ -0,0 +1,40 @@
+// Copyright 2016 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.
+
+// A container to associate type bounds with AST Expression nodes.
+
+#ifndef V8_AST_AST_TYPE_BOUNDS_H_
+#define V8_AST_AST_TYPE_BOUNDS_H_
+
+#include "src/types.h"
+#include "src/zone-containers.h"
+
+namespace v8 {
+namespace internal {
+
+class Expression;
+
+class AstTypeBounds {
+ public:
+  explicit AstTypeBounds(Zone* zone) : bounds_map_(zone) {}
+  ~AstTypeBounds() {}
+
+  Bounds get(Expression* expression) const {
+    ZoneMap<Expression*, Bounds>::const_iterator i =
+        bounds_map_.find(expression);
+    return (i != bounds_map_.end()) ? i->second : Bounds::Unbounded();
+  }
+
+  void set(Expression* expression, Bounds bounds) {
+    bounds_map_[expression] = bounds;
+  }
+
+ private:
+  ZoneMap<Expression*, Bounds> bounds_map_;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_AST_AST_TYPE_BOUNDS_H_