Factor out some platform-independent code into the shared cfg.cc.

src/arm/cfg-arm.cc

Index: src/arm/cfg-arm.cc
===================================================================
--- src/arm/cfg-arm.cc	(revision 2643)
+++ src/arm/cfg-arm.cc	(working copy)
@@ -100,19 +100,6 @@
 }
 
 
-void PositionInstr::Compile(MacroAssembler* masm) {
-  if (FLAG_debug_info && pos_ != RelocInfo::kNoPosition) {
-    __ RecordStatementPosition(pos_);
-    __ RecordPosition(pos_);
-  }
-}
-
-
-void MoveInstr::Compile(MacroAssembler* masm) {
-  location()->Move(masm, value());
-}
-
-
 void BinaryOpInstr::Compile(MacroAssembler* masm) {
   // The right-hand value should not be on the stack---if it is a
   // compiler-generated temporary it is in the accumulator.