Add pass to remove empty blocks and recompute fall-through targets.

runtime/vm/flow_graph_compiler_mips.cc

Index: runtime/vm/flow_graph_compiler_mips.cc
diff --git a/runtime/vm/flow_graph_compiler_mips.cc b/runtime/vm/flow_graph_compiler_mips.cc
index e3c0cd6c380fb34d037d7ce5ce8b0050b71f583a..517ae55fac248e980004a614597bcaa665f86746 100644
--- a/runtime/vm/flow_graph_compiler_mips.cc
+++ b/runtime/vm/flow_graph_compiler_mips.cc
@@ -15,7 +15,7 @@ FlowGraphCompiler::~FlowGraphCompiler() {
   // BlockInfos are zone-allocated, so their destructors are not called.
   // Verify the labels explicitly here.
   for (int i = 0; i < block_info_.length(); ++i) {
-    ASSERT(!block_info_[i]->label.IsLinked());
+    ASSERT(!block_info_[i]->jump_label()->IsLinked());
   }
 }