Implement a variation of scalar replacement for non-escaping allocations.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index aa85a5100bd602ab720682b55655a6e001e6ef9f..1a095e67c87dff0e7fcee1df9c6cbbb5317a29a9 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -7528,6 +7528,15 @@ intptr_t DeoptInfo::Instruction(intptr_t index) const {
 }
 
 
+intptr_t DeoptInfo::FrameSize() const {
+  intptr_t pos = 0;
+  while (Instruction(pos) == DeoptInstr::kMaterializeObject) {
+    pos++;
+  }
+  return TranslationLength() - pos;
+}
+
+
 intptr_t DeoptInfo::TranslationLength() const {
   intptr_t length = Length();
   if (Instruction(length - 1) != DeoptInstr::kSuffix) return length;