fix #26965, allow promotion from type param upper bound in strong mode

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.
 
-### Analyzer
+### Strong Mode
 
-*   Strong mode breaking change - infer generic type arguments from the
+*   New feature - an option to disable implicit casts
+    (SDK issue [26583](https://github.com/dart-lang/sdk/issues/26583)),
+    see the [documentation](https://github.com/dart-lang/dev_compiler/blob/master/doc/STATIC_SAFETY.md#disable-implicit-casts)
+    for usage instructions and examples.
+
+*   New feature - an option to disable implicit dynamic
+    (SDK issue [25573](https://github.com/dart-lang/sdk/issues/25573)),
+    see the [documentation](https://github.com/dart-lang/dev_compiler/blob/master/doc/STATIC_SAFETY.md#disable-implicit-dynamic)
+    for usage instructions and examples.
+
+*   Breaking change - infer generic type arguments from the
     constructor invocation arguments
     (SDK issue [25220](https://github.com/dart-lang/sdk/issues/25220))
 
     ```dart
     var map = new Map<String, String>();
 
     // infer: Map<String, String>
     var otherMap = new Map.from(map);
     ```
 
-*   Strong mode breaking change - infer local function return type
+*   Breaking change - infer local function return type
     (SDK issue [26414](https://github.com/dart-lang/sdk/issues/26414))
 
     ```dart
     void main() {
       // infer: return type is int
       f() { return 40; }
       int y = f() + 2; // type checks
       print(y);
     }
     ```
 
+*   Breaking change - allow type promotion from a generic type parameter
+    (SDK issue [26414](https://github.com/dart-lang/sdk/issues/26965))
+
+    ```dart
+    void fn/*<T>*/(/*=T*/ object) {
+      if (object is String) {
+        // Treat `object` as `String` inside this block.
+        // But it will require a cast to pass it to something that expects `T`.
+        print(object.substring(1));
+      }
+    }
+    ```
+
 ### Tool Changes
 
 * `dartfmt` - upgraded to v0.2.9
   * Support trailing commas in argument and parameter lists.
   * Gracefully handle read-only files.
   * About a dozen other bug fixes.
 
 * Pub
   * Added the ability for packages to declare a constraint on the [Flutter][]
     SDK:
@@ skipping 1080 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.