Improve and simplify removal of unreachable code

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 998b73b62e9242a6dd2393a919f199f2af5c1859..0c83ac63b533f0eaf1ba4a3a8294eceaf6906b0e 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -991,10 +991,10 @@ LInstruction* LChunkBuilder::DoGoto(HGoto* instr) {
 LInstruction* LChunkBuilder::DoBranch(HBranch* instr) {
   HValue* value = instr->value();
   if (value->EmitAtUses()) {
-    HBasicBlock* successor = HConstant::cast(value)->BooleanValue()
-        ? instr->FirstSuccessor()
-        : instr->SecondSuccessor();
-    return new(zone()) LGoto(successor->block_id());
+    ASSERT(value->IsConstant());
+    ASSERT(!value->representation().IsDouble());
+    return ElideControlInstruction(instr,
+                                   HConstant::cast(value)->BooleanValue());
   }
 
   LBranch* result = new(zone()) LBranch(UseRegister(value));
@@ -1727,6 +1727,13 @@ LInstruction* LChunkBuilder::DoCompareNumericAndBranch(
 
 LInstruction* LChunkBuilder::DoCompareObjectEqAndBranch(
     HCompareObjectEqAndBranch* instr) {
+  if (instr->left()->IsConstant() && instr->right()->IsConstant()) {
+    bool comparison_result =
+        HConstant::cast(instr->left())->SameConstantObject(
+            HConstant::cast(instr->right()));
+    return ElideControlInstruction(instr, comparison_result);
+  }
+
   LOperand* left = UseRegisterAtStart(instr->left());
   LOperand* right = UseRegisterAtStart(instr->right());
   return new(zone()) LCmpObjectEqAndBranch(left, right);