Revert r28050 due to crashes with --optimization-counter-threshold=5.

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
===================================================================
--- runtime/vm/intermediate_language.cc	(revision 28051)
+++ runtime/vm/intermediate_language.cc	(working copy)
@@ -980,30 +980,6 @@
 }
 
 
-bool BlockEntryInstr::IsEmptyBlock() {
-  return !HasParallelMove() &&
-      next()->IsGoto() &&
-      !next()->AsGoto()->HasParallelMove() &&
-      (!IsJoinEntry() || (AsJoinEntry()->phis() == NULL));
-}
-
-
-void BlockEntryInstr::ClearAllInstructions() {
-  JoinEntryInstr* join = this->AsJoinEntry();
-  if (join != NULL) {
-    for (PhiIterator it(join); !it.Done(); it.Advance()) {
-      it.Current()->UnuseAllInputs();
-    }
-  }
-  UnuseAllInputs();
-  for (ForwardInstructionIterator it(this);
-       !it.Done();
-       it.Advance()) {
-    it.Current()->UnuseAllInputs();
-  }
-}
-
-
 void JoinEntryInstr::InsertPhi(intptr_t var_index, intptr_t var_count) {
   // Lazily initialize the array of phis.
   // Currently, phis are stored in a sparse array that holds the phi