Resubmit change 6302 after fixing the compiler warning on older GCC compiler versions:

vm/object.h

Index: vm/object.h
===================================================================
--- vm/object.h	(revision 6329)
+++ vm/object.h	(working copy)
@@ -130,6 +130,7 @@
     return raw()->ptr();                                                       \
   }                                                                            \
   SNAPSHOT_READER_SUPPORT(object)                                              \
+  friend class DartFrame;                                                      \
 
 class Object {
  public:
@@ -374,7 +375,8 @@
   static void InitializeObject(uword address, intptr_t size);
 
   cpp_vtable* vtable_address() const {
-    return reinterpret_cast<cpp_vtable*>(reinterpret_cast<word>(this));
+    uword vtable_addr = reinterpret_cast<uword>(this);
+    return reinterpret_cast<cpp_vtable*>(vtable_addr);
   }
 
   static cpp_vtable handle_vtable_;
@@ -2076,10 +2078,10 @@
   void SetCode(const Code& code) const;
 
   // Return the offset of the highest stack slot that has an object.
-  intptr_t Maximum() const;
+  intptr_t MaximumBitOffset() const { return raw_ptr()->max_set_bit_offset_; }
 
   // Return the offset of the lowest stack slot that has an object.
-  intptr_t Minimum() const;
+  intptr_t MinimumBitOffset() const { return raw_ptr()->min_set_bit_offset_; }
 
   static intptr_t InstanceSize() {
     ASSERT(sizeof(RawStackmap) == OFFSET_OF(RawStackmap, data_));
@@ -2088,19 +2090,24 @@
   static intptr_t InstanceSize(intptr_t size) {
     return RoundedAllocationSize(sizeof(RawStackmap) + (size * kWordSize));
   }
-  static RawStackmap* New(uword pc, const Code& code, BitmapBuilder* bmap);
+  static RawStackmap* New(uword pc, BitmapBuilder* bmap);
 
  private:
   inline intptr_t SizeInBits() const;
 
+  void SetMinBitOffset(intptr_t value) const {
+    raw_ptr()->min_set_bit_offset_ = value;
+  }
+  void SetMaxBitOffset(intptr_t value) const {
+    raw_ptr()->max_set_bit_offset_ = value;
+  }
+
   bool InRange(intptr_t offset) const { return offset < SizeInBits(); }
 
   bool GetBit(intptr_t bit_offset) const;
   void SetBit(intptr_t bit_offset, bool value) const;
 
   void set_bitmap_size_in_bytes(intptr_t value) const;
-  void set_pc(uword value) const;
-  void set_code(const Code& code) const;
 
   HEAP_OBJECT_IMPLEMENTATION(Stackmap, Object);
   friend class Class;
@@ -2196,6 +2203,7 @@
     return raw_ptr()->stackmaps_;
   }
   void set_stackmaps(const Array& maps) const;
+  RawStackmap* GetStackmap(uword pc, Array* stackmaps, Stackmap* map) const;
 
   RawLocalVarDescriptors* var_descriptors() const {
     return raw_ptr()->var_descriptors_;