Make JSON parsing work as a chunked conversion sink.

runtime/lib/double_patch.dart

 // Copyright (c) 2012, 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.
 // Dart core library.
 
 // VM implementation of double.
 
 patch class double {
 
   static double _nativeParse(String str,
@@ skipping 62 matching lines @@
         int expPart = int._tryParseSmi(str, i, end - 1);
         if (expPart == null) return null;
         exponent += expPart;
         break;
       } else {
         return null;
       }
     }
     if (!digitsSeen) return null;  // No digits.
     if (exponent == 0) return sign * doubleValue;
-    // Powers of 10 up to 10^22 are representable as doubles.
-    // Powers of 10 above that are only approximate due to lack of precission.
-    const P10 = const [
-                            1.0,  /*  0 */
-                           10.0,
-                          100.0,
-                         1000.0,
-                        10000.0,
-                       100000.0,  /*  5 */
-                      1000000.0,
-                     10000000.0,
-                    100000000.0,
-                   1000000000.0,
-                  10000000000.0,  /* 10 */
-                 100000000000.0,
-                1000000000000.0,
-               10000000000000.0,
-              100000000000000.0,
-             1000000000000000.0,  /*  15 */
-            10000000000000000.0,
-           100000000000000000.0,
-          1000000000000000000.0,
-         10000000000000000000.0,
-        100000000000000000000.0,  /*  20 */
-       1000000000000000000000.0,
-      10000000000000000000000.0,
-    ];
+    const P10 = POWERS_OF_TEN;  // From shared library
     if (exponent < 0) {
       int negExponent = -exponent;
       if (negExponent >= P10.length) return null;
       return sign * (doubleValue / P10[negExponent]);
     }
     if (exponent >= P10.length) return null;
     return sign * (doubleValue * P10[exponent]);
   }
 
   static double _parse(var str) {
@@ skipping 10 matching lines @@
   /* patch */ static double parse(String str,
                                   [double onError(String str)]) {
     var result = _parse(str);
     if (result == null) {
       if (onError == null) throw new FormatException("Invalid double", str);
       return onError(str);
     }
     return result;
   }
 }