Precompilation: canonicalize Instructions in PRODUCT mode.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 1715a13a293a8ae1b354697908eb522cd39752a3..23cae39f5ee57a884e94b2fbafbaef3f91c3c0c2 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -3823,6 +3823,14 @@ class Instructions : public Object {
         entry_point - HeaderSize() + kHeapObjectTag);
   }
 
+  bool Equals(const Instructions& other) const {
+    if (size() != other.size()) {
+      return false;
+    }
+    NoSafepointScope no_safepoint;
+    return memcmp(raw_ptr(), other.raw_ptr(), InstanceSize(size())) == 0;
+  }
+
  private:
   void set_size(intptr_t size) const {
     StoreNonPointer(&raw_ptr()->size_, size);
@@ -4606,6 +4614,7 @@ class Code : public Object {
   friend class Class;
   friend class SnapshotWriter;
   friend class CodePatcher;  // for set_instructions
+  friend class Precompiler;  // for set_instructions
   // So that the RawFunction pointer visitor can determine whether code the
   // function points to is optimized.
   friend class RawFunction;