Unbox phis that were proven to be of type Double.

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 8b14ea6ab7f06af3bdb77229f5479fb644a53cf9..f30a02cf433c5435f5790caf8c74f7b7c89e2a5f 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -167,9 +167,11 @@ Isolate::Isolate()
       spawn_data_(NULL),
       gc_prologue_callbacks_(),
       gc_epilogue_callbacks_(),
-      deopt_registers_copy_(NULL),
+      deopt_cpu_registers_copy_(NULL),
+      deopt_xmm_registers_copy_(NULL),
       deopt_frame_copy_(NULL),
-      deopt_frame_copy_size_(0) {
+      deopt_frame_copy_size_(0),
+      deferred_doubles_(NULL) {
 }