Lazy implementation of final variables.

lib/compiler/implementation/tree/nodes.dart

Index: lib/compiler/implementation/tree/nodes.dart
diff --git a/lib/compiler/implementation/tree/nodes.dart b/lib/compiler/implementation/tree/nodes.dart
index f3d37ec5e0467ee81f3b57eaafd24c0b0318e886..8b3d3f5233bf1bd00fd1d989f17b41a19a3d7572 100644
--- a/lib/compiler/implementation/tree/nodes.dart
+++ b/lib/compiler/implementation/tree/nodes.dart
@@ -1136,6 +1136,7 @@ class Modifiers extends Node {
   bool isConst() => (flags & FLAG_CONST) != 0;
   bool isFactory() => (flags & FLAG_FACTORY) != 0;
   bool isExternal() => (flags & FLAG_EXTERNAL) != 0;
+  bool isFinalOrConst() => (flags & (FLAG_FINAL | FLAG_CONST)) != 0;
 
   String toString() {
     LinkBuilder<String> builder = new LinkBuilder<String>();
@@ -1678,7 +1679,7 @@ class CatchBlock extends Node {
   final Token onKeyword;
   final Token catchKeyword;
 
-  CatchBlock(this.type, this.formals, this.block, 
+  CatchBlock(this.type, this.formals, this.block,
              this.onKeyword, this.catchKeyword);
 
   CatchBlock asCatchBlock() => this;