Drop fromBind utility (#59)

Replace with `StreamTransformer.fromBind` which is now in the SDK.

Author: natebosch

lib/src/bind.dart

@@ -4,8 +4,6 @@
 
 import 'dart:async';
 
-import 'bind.dart';
-
 /// Combines two transformers into one.
 ///
 /// This is most useful to keep a reference to the combination and use it in
@@ -21,4 +19,5 @@ import 'bind.dart';
 /// ```
 StreamTransformer<S, T> chainTransformers<S, I, T>(
         StreamTransformer<S, I> first, StreamTransformer<I, T> second) =>
-    fromBind((values) => values.transform(first).transform(second));
+    StreamTransformer.fromBind(
+        (values) => values.transform(first).transform(second));

lib/src/chain_transformers.dart

@@ -4,8 +4,6 @@
 
 import 'dart:async';
 
-import 'bind.dart';
-
 /// Models a [Stream.map] callback as a [StreamTransformer].
 ///
 /// This is most useful to pass to functions that take a [StreamTransformer]
@@ -19,4 +17,4 @@ import 'bind.dart';
 ///     map((v) => '$v'));
 /// ```
 StreamTransformer<S, T> map<S, T>(T convert(S event)) =>
-    fromBind((stream) => stream.map(convert));
+    StreamTransformer.fromBind((stream) => stream.map(convert));

lib/src/map.dart

@@ -1,15 +1,14 @@
 // Copyright (c) 2017, 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.
-import 'dart:async';
 
-import 'bind.dart';
+import 'dart:async';
 
 /// Scan is like fold, but instead of producing a single value it yields
 /// each intermediate accumulation.
 StreamTransformer<S, T> scan<S, T>(
         T initialValue, T combine(T previousValue, S element)) =>
-    fromBind((stream) {
+    StreamTransformer.fromBind((stream) {
       var accumulated = initialValue;
       return stream.map((value) => accumulated = combine(accumulated, value));
     });

lib/src/scan.dart

@@ -4,7 +4,6 @@
 
 import 'dart:async';
 
-import 'bind.dart';
 import 'followed_by.dart';
 
 /// Emits [initial] before any values from the original stream.
@@ -27,7 +26,7 @@ StreamTransformer<T, T> startWithMany<T>(Iterable<T> initial) =>
 /// the original stream is a broadcast stream it will miss any events which
 /// occur before [initial] closes.
 StreamTransformer<T, T> startWithStream<T>(Stream<T> initial) =>
-    fromBind((values) {
+    StreamTransformer.fromBind((values) {
       if (values.isBroadcast && !initial.isBroadcast) {
         initial = initial.asBroadcastStream();
       }

lib/src/start_with.dart

@@ -5,7 +5,7 @@ homepage: https://www.github.com/dart-lang/stream_transform
 version: 0.0.15-dev
 
 environment:
-  sdk: ">=2.0.0 <3.0.0"
+  sdk: ">=2.1.0 <3.0.0"
 
 dev_dependencies:
   test: ^1.0.0