Refactor lithium classes to reduce the number of virtual functions.

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
===================================================================
--- src/ia32/lithium-codegen-ia32.cc	(revision 7679)
+++ src/ia32/lithium-codegen-ia32.cc	(working copy)
@@ -681,23 +681,6 @@
 }
 
 
-void LCodeGen::DoLabel(LLabel* label) {
-  if (label->is_loop_header()) {
-    Comment(";;; B%d - LOOP entry", label->block_id());
-  } else {
-    Comment(";;; B%d", label->block_id());
-  }
-  __ bind(label->label());
-  current_block_ = label->block_id();
-  LCodeGen::DoGap(label);
-}
-
-
-void LCodeGen::DoParallelMove(LParallelMove* move) {
-  resolver_.Resolve(move);
-}
-
-
 void LCodeGen::DoGap(LGap* gap) {
   for (int i = LGap::FIRST_INNER_POSITION;
        i <= LGap::LAST_INNER_POSITION;
@@ -715,6 +698,28 @@
 }
 
 
+void LCodeGen::DoInstructionGap(LInstructionGap* instr) {
+  DoGap(instr);
+}
+
+
+void LCodeGen::DoLabel(LLabel* label) {
+  if (label->is_loop_header()) {
+    Comment(";;; B%d - LOOP entry", label->block_id());
+  } else {
+    Comment(";;; B%d", label->block_id());
+  }
+  __ bind(label->label());
+  current_block_ = label->block_id();
+  DoGap(label);
+}
+
+
+void LCodeGen::DoParallelMove(LParallelMove* move) {
+  resolver_.Resolve(move);
+}
+
+
 void LCodeGen::DoParameter(LParameter* instr) {
   // Nothing to do.
 }