Revert "Handle HCheckInstanceType and HIsStringAndBranch in check elimination."

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index e7ef516fbc9f86708b5dd353e1ccda0919536ea8..6303cd13c7a583d13e906651c7cb81e39698c49d 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -3256,27 +3256,11 @@ bool HIsObjectAndBranch::KnownSuccessorBlock(HBasicBlock** block) {
 
 
 bool HIsStringAndBranch::KnownSuccessorBlock(HBasicBlock** block) {
-  if (known_successor_index() != kNoKnownSuccessorIndex) {
-    *block = SuccessorAt(known_successor_index());
-    return true;
-  }
   if (FLAG_fold_constants && value()->IsConstant()) {
     *block = HConstant::cast(value())->HasStringValue()
         ? FirstSuccessor() : SecondSuccessor();
     return true;
   }
-  if (value()->type().IsString()) {
-    *block = FirstSuccessor();
-    return true;
-  }
-  if (value()->type().IsSmi() ||
-      value()->type().IsNull() ||
-      value()->type().IsBoolean() ||
-      value()->type().IsUndefined() ||
-      value()->type().IsJSObject()) {
-    *block = SecondSuccessor();
-    return true;
-  }
   *block = NULL;
   return false;
 }