Introduce number type information in the virtual frame.

src/number-info.h

Index: src/number-info.h
===================================================================
--- src/number-info.h	(revision 0)
+++ src/number-info.h	(revision 0)
@@ -0,0 +1,53 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_NUMBER_INFO_H_
+#define V8_NUMBER_INFO_H_
+
+namespace v8 {
+namespace internal {
+
+class NumberInfo : public AllStatic {
+ public:
+  enum Type {
+    kUnknown = 0,
+    kNumber = 1,
+    kSmi = 3,
+    kHeapNumber = 5,
+    kUninitialized = 7
+  };
+
+  // Return the weakest (least precise) common type.
+  static Type Combine(Type a, Type b) {
+    // Make use of the order of enum values.
+    return static_cast<Type>(a & b);
+  }
+};
+
+} }  // namespace v8::internal
+
+#endif  // V8_NUMBER_INFO_H_