Reapply fast-URI patch.

CHANGELOG.md

 ## 1.19.0
 
 ### Core library changes
 
 * `dart:io`
   * `Socket.connect` with source-address argument is now non-blocking
     on Mac. Was already non-blocking on all other platforms.
   * Report a better error when a bind fails because of a bad source address.
 
 ### Strong Mode
@@ skipping 104 matching lines @@
 * VM: Fixes an optimizer bug involving closures, try, and await
 (SDK issue [26948](https://github.com/dart-lang/sdk/issues/26948))
 
 * Dart2js: Speeds up generated code on Firefox
 (https://codereview.chromium.org/2180533002)
 
 ## 1.18.0 - 2016-07-27
 
 ### Core library changes
 
+* `dart:core`
+  * Improved performance when parsing some common URIs.
+  * Fixed bug in `Uri.resolve` (SDK issue [26804](https://github.com/dart-lang/sdk/issues/26804)).
 * `dart:io`
   * Adds file locking modes `FileLock.BLOCKING_SHARED` and
     `FileLock.BLOCKING_EXCLUSIVE`.
 
 ## 1.17.1 - 2016-06-10
 
 Patch release, resolves two issues:
 
 * VM: Fixes a bug that caused crashes in async functions.
 (SDK issue [26668](https://github.com/dart-lang/sdk/issues/26668))
@@ skipping 1019 matching lines @@
     they will keep the Dart process alive until they time out. This fixes the
     handling of persistent connections. Previously, the client would shut down
     immediately after a request.
 
   * **Breaking change:** `HttpServer` no longer compresses all traffic by
     default. The new `autoCompress` property can be set to `true` to re-enable
     compression.
 
 * `dart:isolate`: `Isolate.spawnUri` added the optional `packageRoot` argument,
   which controls how it resolves `package:` URIs.