dart2js cps: Do not treat final field reads as effectively constant.

pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart

Index: pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart
diff --git a/pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart b/pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart
index 7f1ff4f00a4a1eb535f50da3303eaf38f15de379..5cd7ee7f9e1fdb4605dd0641ea1a901bee7b4e07 100644
--- a/pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart
+++ b/pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart
@@ -355,7 +355,6 @@ class StatementRewriter extends Transformer implements Pass {
            exp is This ||
            exp is CreateInvocationMirror ||
            exp is GetStatic && exp.element.isFunction ||
-           exp is GetField && exp.objectIsNotNull && exp.field.isFinal ||
            exp is Interceptor ||
            exp is ApplyBuiltinOperator ||
            exp is VariableUse && constantEnvironment.containsKey(exp.variable);