Use ConstExp for storing constants.

sdk/lib/_internal/compiler/implementation/dart_backend/backend_ast_emitter.dart

Index: sdk/lib/_internal/compiler/implementation/dart_backend/backend_ast_emitter.dart
diff --git a/sdk/lib/_internal/compiler/implementation/dart_backend/backend_ast_emitter.dart b/sdk/lib/_internal/compiler/implementation/dart_backend/backend_ast_emitter.dart
index 8cf19cc9041cf321923048e918d95763e2ebe8c3..cbc86b0e5c588b079aab7904ae705a3726634c47 100644
--- a/sdk/lib/_internal/compiler/implementation/dart_backend/backend_ast_emitter.dart
+++ b/sdk/lib/_internal/compiler/implementation/dart_backend/backend_ast_emitter.dart
@@ -670,7 +670,7 @@ class ConstantEmitter extends ConstExpVisitor<Expression> {
   ASTEmitter parent;
   ConstantEmitter(this.parent);
 
-  Expression visitPrimitive(PrimitiveConstExp exp) {
+  Expression handlePrimitiveConstant(dart2js.PrimitiveConstant value) {
     // Num constants may be negative, while literals must be non-negative:
     // Literals are non-negative in the specification, and a negated literal
     // parses as a call to unary `-`. The AST unparser assumes literals are
@@ -678,13 +678,17 @@ class ConstantEmitter extends ConstExpVisitor<Expression> {
     // the predecrement operator.
     // Translate such constants into their positive value wrapped by
     // the unary minus operator.
-    if (exp.constant is dart2js.NumConstant) {
-      dart2js.NumConstant numConstant = exp.constant;
+    if (value is dart2js.NumConstant) {
+      dart2js.NumConstant numConstant = value;
       if (numConstant.value.isNegative) {
         return negatedLiteral(numConstant);
       }
     }
-    return new Literal(exp.constant);
+    return new Literal(value);
+  }
+
+  Expression visitPrimitive(PrimitiveConstExp exp) {
+    return handlePrimitiveConstant(exp.value);
   }
 
   /// Given a negative num constant, returns the corresponding positive
@@ -769,6 +773,24 @@ class ConstantEmitter extends ConstExpVisitor<Expression> {
                ..element = exp.element;
   }
 
+  @override

[sigurdm, 2014/09/17 10:29:41]

Maybe add override to all the overriding methods

[Johnni Winther, 2014/09/17 12:20:40]

Done.

+  Expression visitBinary(BinaryConstExp exp) {
+    return handlePrimitiveConstant(exp.value);
+  }
+
+  @override
+  Expression visitConditional(ConditionalConstExp exp) {
+    if (exp.condition.value.isTrue) {
+      return exp.trueExp.accept(this);
+    } else {
+      return exp.falseExp.accept(this);
+    }
+  }
+
+  @override
+  Expression visitUnary(UnaryConstExp exp) {
+    return handlePrimitiveConstant(exp.value);
+  }
 }
 
 /// Moves function parameters into a separate variable if one of its uses is