Optimize conditional branches that have same true/false targets.

runtime/vm/flow_graph_compiler.cc

Index: runtime/vm/flow_graph_compiler.cc
===================================================================
--- runtime/vm/flow_graph_compiler.cc	(revision 27294)
+++ runtime/vm/flow_graph_compiler.cc	(working copy)
@@ -170,13 +170,6 @@
 }
 
 
-static bool IsEmptyBlock(BlockEntryInstr* block) {
-  return !block->HasParallelMove() &&
-         block->next()->IsGoto() &&
-         !block->next()->AsGoto()->HasParallelMove();
-}
-
-
 void FlowGraphCompiler::CompactBlock(BlockEntryInstr* block) {
   BlockInfo* block_info = block_info_[block->postorder_number()];
 
@@ -185,7 +178,7 @@
   }
   block_info->mark();
 
-  if (IsEmptyBlock(block)) {
+  if (block->IsEmptyBlock()) {
     BlockEntryInstr* target = block->next()->AsGoto()->successor();
     CompactBlock(target);
     block_info->set_jump_label(GetJumpLabel(target));