Add support for near labels....

src/x64/assembler-x64.h

Index: src/x64/assembler-x64.h
===================================================================
--- src/x64/assembler-x64.h	(revision 5449)
+++ src/x64/assembler-x64.h	(working copy)
@@ -1005,6 +1005,7 @@
   // but it may be bound only once.
 
   void bind(Label* L);  // binds an unbound label L to the current code position
+  void bind(NearLabel* L);
 
   // Calls
   // Call near relative 32-bit displacement, relative to next instruction.
@@ -1029,10 +1030,16 @@
   // Jump near absolute indirect (m64)
   void jmp(const Operand& src);
 
+  // Short jump
+  void jmp(NearLabel* L);
+
   // Conditional jumps
   void j(Condition cc, Label* L);
   void j(Condition cc, Handle<Code> target, RelocInfo::Mode rmode);
 
+  // Conditional short jump
+  void j(Condition cc, NearLabel* L, Hint hint = no_hint);
+
   // Floating-point operations
   void fld(int i);
 
@@ -1196,6 +1203,7 @@
  private:
   byte* addr_at(int pos)  { return buffer_ + pos; }
   byte byte_at(int pos)  { return buffer_[pos]; }
+  void set_byte_at(int pos, byte value) { buffer_[pos] = value; }
   uint32_t long_at(int pos)  {
     return *reinterpret_cast<uint32_t*>(addr_at(pos));
   }
@@ -1371,7 +1379,6 @@
   // labels
   // void print(Label* L);
   void bind_to(Label* L, int pos);
-  void link_to(Label* L, Label* appendix);
 
   // record reloc info for current pc_
   void RecordRelocInfo(RelocInfo::Mode rmode, intptr_t data = 0);