Optimize redundant HCompareMap instructions with known successors.

src/arm/lithium-arm.cc

Index: src/arm/lithium-arm.cc
diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index e670d343d9d8dee26068c29912258588dc2cfd2a..38509a6ea8f2e43b1bb19b5e68f603a720fd2f12 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -942,6 +942,9 @@ LInstruction* LChunkBuilder::DoDebugBreak(HDebugBreak* instr) {
 
 
 LInstruction* LChunkBuilder::DoCompareMap(HCompareMap* instr) {
+  LInstruction* goto_instr = CheckElideControlInstruction(instr);
+  if (goto_instr != NULL) return goto_instr;
+
   ASSERT(instr->value()->representation().IsTagged());
   LOperand* value = UseRegisterAtStart(instr->value());
   LOperand* temp = TempRegister();