Start supporting fixed length and immutable lists.

dart/frog/leg/ssa/nodes.dart

Index: dart/frog/leg/ssa/nodes.dart
diff --git a/dart/frog/leg/ssa/nodes.dart b/dart/frog/leg/ssa/nodes.dart
index 48e66414f9261cb1f8545a5c7c2b9f08f9a48325..0787b22e2fd0ee5cfcb8cc11902a5cf2c7a4c9f1 100644
--- a/dart/frog/leg/ssa/nodes.dart
+++ b/dart/frog/leg/ssa/nodes.dart
@@ -2120,11 +2120,12 @@ class HStaticStore extends HInstruction {
 }
 
 class HLiteralList extends HInstruction {
-  HLiteralList(inputs) : super(inputs);
+  HLiteralList(inputs, this.isConst) : super(inputs);
   toString() => 'literal list';
   accept(HVisitor visitor) => visitor.visitLiteralList(this);
   HType computeType() => HType.ARRAY;
   bool hasExpectedType() => true;
+  final bool isConst; // TODO(floitsch): Remove when CTC handles arrays.
 
   void prepareGvn() {
     assert(!hasSideEffects());