Fixed some undefined behavior in our external header.

include/v8.h

 // Copyright 2012 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.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
@@ skipping 5581 matching lines @@
 // Tag information for Smi.
 const int kSmiTag = 0;
 const int kSmiTagSize = 1;
 const intptr_t kSmiTagMask = (1 << kSmiTagSize) - 1;
 
 template <size_t ptr_size> struct SmiTagging;
 
 template<int kSmiShiftSize>
 V8_INLINE internal::Object* IntToSmi(int value) {
   int smi_shift_bits = kSmiTagSize + kSmiShiftSize;
-  intptr_t tagged_value =
-      (static_cast<intptr_t>(value) << smi_shift_bits) | kSmiTag;
+  uintptr_t tagged_value =
+      (static_cast<uintptr_t>(value) << smi_shift_bits) | kSmiTag;
   return reinterpret_cast<internal::Object*>(tagged_value);
 }
 
 // Smi constants for 32-bit systems.
 template <> struct SmiTagging<4> {
   enum { kSmiShiftSize = 0, kSmiValueSize = 31 };
   static int SmiShiftSize() { return kSmiShiftSize; }
   static int SmiValueSize() { return kSmiValueSize; }
   V8_INLINE static int SmiToInt(const internal::Object* value) {
     int shift_bits = kSmiTagSize + kSmiShiftSize;
@@ skipping 149 matching lines @@
   }
 
   V8_INLINE static uint8_t GetNodeFlag(internal::Object** obj, int shift) {
       uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + kNodeFlagsOffset;
       return *addr & static_cast<uint8_t>(1U << shift);
   }
 
   V8_INLINE static void UpdateNodeFlag(internal::Object** obj,
                                        bool value, int shift) {
       uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + kNodeFlagsOffset;
-      uint8_t mask = static_cast<uint8_t>(1 << shift);
+      uint8_t mask = static_cast<uint8_t>(1U << shift);
       *addr = static_cast<uint8_t>((*addr & ~mask) | (value << shift));
   }
 
   V8_INLINE static uint8_t GetNodeState(internal::Object** obj) {
     uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + kNodeFlagsOffset;
     return *addr & kNodeStateMask;
   }
 
   V8_INLINE static void UpdateNodeState(internal::Object** obj,
                                         uint8_t value) {
@@ skipping 1040 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_