Revert "Remove Registry from registerMetadataConstant" and "Serialize metadata"

pkg/compiler/lib/src/js_emitter/constant_ordering.dart

Index: pkg/compiler/lib/src/js_emitter/constant_ordering.dart
diff --git a/pkg/compiler/lib/src/js_emitter/constant_ordering.dart b/pkg/compiler/lib/src/js_emitter/constant_ordering.dart
index 27651c20e31230b870f2de009b833e4608538f06..a2a0d7d5fccadb0f77d2b1c4314f5d09c0b4c638 100644
--- a/pkg/compiler/lib/src/js_emitter/constant_ordering.dart
+++ b/pkg/compiler/lib/src/js_emitter/constant_ordering.dart
@@ -76,10 +76,6 @@ class _CompareVisitor implements ConstantValueVisitor<int, ConstantValue> {
     return 0;
   }
 
-  int visitNonConstant(NonConstantValue a, NonConstantValue b) {
-    return 0;
-  }
-
   int visitInt(IntConstantValue a, IntConstantValue b) {
     return a.primitiveValue.compareTo(b.primitiveValue);
   }
@@ -193,14 +189,12 @@ class _KindVisitor implements ConstantValueVisitor<int, Null> {
   static const int INTERCEPTOR = 11;
   static const int SYNTHETIC = 12;
   static const int DEFERRED = 13;
-  static const int NONCONSTANT = 13;
 
   static int kind(ConstantValue constant) =>
       constant.accept(const _KindVisitor(), null);
 
   int visitFunction(FunctionConstantValue a, _) => FUNCTION;
   int visitNull(NullConstantValue a, _) => NULL;
-  int visitNonConstant(NonConstantValue a, _) => NONCONSTANT;
   int visitInt(IntConstantValue a, _) => INT;
   int visitDouble(DoubleConstantValue a, _) => DOUBLE;
   int visitBool(BoolConstantValue a, _) => BOOL;