[crankshaft] Remove the useless HMapEnumLength instruction.

src/crankshaft/ia32/lithium-ia32.cc

Index: src/crankshaft/ia32/lithium-ia32.cc
diff --git a/src/crankshaft/ia32/lithium-ia32.cc b/src/crankshaft/ia32/lithium-ia32.cc
index 3648ccffca989865241e0b28c4788e8e8ee8a9da..8e0e98eb645df171803ec3f3bfa2308d4e315d3d 100644
--- a/src/crankshaft/ia32/lithium-ia32.cc
+++ b/src/crankshaft/ia32/lithium-ia32.cc
@@ -1788,12 +1788,6 @@ LInstruction* LChunkBuilder::DoClassOfTestAndBranch(
 }
 
 
-LInstruction* LChunkBuilder::DoMapEnumLength(HMapEnumLength* instr) {
-  LOperand* map = UseRegisterAtStart(instr->value());
-  return DefineAsRegister(new(zone()) LMapEnumLength(map));
-}
-
-
 LInstruction* LChunkBuilder::DoSeqStringGetChar(HSeqStringGetChar* instr) {
   LOperand* string = UseRegisterAtStart(instr->string());
   LOperand* index = UseRegisterOrConstantAtStart(instr->index());