We no longer have a separate engine repo. (#161400)

Closes flutter/flutter#161351.

Author: matanlurey

docs/about/Why-we-have-a-separate-engine-repo.md

@@ -371,8 +371,7 @@ All licenses included in this manner must have been reviewed and determined to b
 
 All such "third party code" must either be a fork for which we take full responsibility, or there must be an automated rolling mechanism that keeps the code up to date when the upstream source changes.
 
-In general it is _strongly_ recommended that we avoid any such code unless strictly necessary. In particular, we aim for all code in the flutter/flutter repository to be [single-licensed](../about/Why-we-have-a-separate-engine-repo.md#licensing), which is why it does not contain any "third party code" at all.
-
+In general it is _strongly_ recommended that we avoid any such code unless strictly necessary.
 
 ## Documentation (dartdocs, javadocs, etc)
 

docs/contributing/Style-guide-for-Flutter-repo.md

@@ -29,4 +29,3 @@ This is an index of team-facing documentation for the [flutter/engine repository
 - [Upgrading Engine's Android API version](https://github.com/flutter/flutter/blob/master/docs/platforms/android/Upgrading-Engine's-Android-API-version.md)
 - [Using the Dart Development Service (DDS) and Flutter DevTools with a custom Flutter Engine Embedding](./Using-the-Dart-Development-Service-(DDS)-and-Flutter-DevTools-with-a-custom-Flutter-Engine-Embedding.md)
 - [Using Sanitizers with the Flutter Engine](./Using-Sanitizers-with-the-Flutter-Engine.md)
-- [Why we have a separate engine repo](https://github.com/flutter/flutter/blob/master/docs/about/Why-we-have-a-separate-engine-repo.md)