Support encoding of NaN, infinity and negative infinity.

pkg/compiler/lib/src/serialization/json_serializer.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.serialization.json;
 
 import 'dart:convert';
 
 import 'keys.dart';
 import 'serialization.dart';
 import 'values.dart';
 
 /// Serialization encoder for JSON.
 class JsonSerializationEncoder implements SerializationEncoder {
   const JsonSerializationEncoder();
 
   String encode(ObjectValue objectValue) {
-    return new JsonEncoder.withIndent(' ')
-        .convert(const JsonValueEncoder().convert(objectValue));
+    try {
+      return new JsonEncoder.withIndent(' ')
+          .convert(const JsonValueEncoder().convert(objectValue));
+    } on JsonUnsupportedObjectError catch (e) {
+      throw 'Error encoding `${e.unsupportedObject}` '
+          '(${e.unsupportedObject.runtimeType})';
+    }
   }
 }
 
 /// Serialization decoder for JSON.
 class JsonSerializationDecoder implements SerializationDecoder {
   const JsonSerializationDecoder();
 
   Map decode(String text) => JSON.decode(text);
 
   /// Returns the name of the [key] which used for to store a [Key] into a
@@ skipping 11 matching lines @@
   @override
   visit(Value value, [arg]) => value.accept(this, arg);
 
   @override
   bool visitBool(BoolValue value, arg) => value.value;
 
   @override
   visitConstant(ConstantValue value, arg) => visit(value.id);
 
   @override
-  double visitDouble(DoubleValue value, arg) => value.value;
+  visitDouble(DoubleValue value, arg) {
+    double d = value.value;
+    if (d.isNaN) {
+      return 'NaN';
+    } else if (d.isInfinite) {
+      if (d.isNegative) {
+        return '-Infinity';
+      } else {
+        return 'Infinity';
+      }
+    }
+    return d;
+  }
 
   @override
   visitElement(ElementValue value, arg) => visit(value.id);
 
   @override
   visitEnum(EnumValue value, arg) => value.value.index;
 
   @override
   int visitInt(IntValue value, arg) => value.value;
 
@@ skipping 143 matching lines @@
   @override
   void visitType(TypeValue value, String indentation) {
     buffer.write('Type(${value.id}):${value.type}');
   }
 
   @override
   void visitUri(UriValue value, String indentation) {
     buffer.write('Uri(${value.value})');
   }
 }