Compress deopt instructions in memory using variable length encoding.

runtime/vm/flow_graph_compiler_arm64.cc

Index: runtime/vm/flow_graph_compiler_arm64.cc
diff --git a/runtime/vm/flow_graph_compiler_arm64.cc b/runtime/vm/flow_graph_compiler_arm64.cc
index 6da5f28dc6122241fe3f0c3514382068d0197cb1..b853e5d5fcb354222fdd1162c750f4bf3d565c73 100644
--- a/runtime/vm/flow_graph_compiler_arm64.cc
+++ b/runtime/vm/flow_graph_compiler_arm64.cc
@@ -74,12 +74,12 @@ void FlowGraphCompiler::ExitIntrinsicMode() {
 }
 
 
-RawDeoptInfo* CompilerDeoptInfo::CreateDeoptInfo(FlowGraphCompiler* compiler,
+RawTypedData* CompilerDeoptInfo::CreateDeoptInfo(FlowGraphCompiler* compiler,
                                                  DeoptInfoBuilder* builder,
                                                  const Array& deopt_table) {
   if (deopt_env_ == NULL) {
     ++builder->current_info_number_;
-    return DeoptInfo::null();
+    return TypedData::null();
   }
 
   intptr_t stack_height = compiler->StackSize();