Merge pull request #306 from UnityTech/release_1.5.4

Release 1.5.4

Author: zhuxingwei

CHANGELOG.md

@@ -9,3 +9,20 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### This is the first release of *Unity Package UIWidgets*.
 
 *just the first release*
+
+
+## [1.5.4-release] - 2019-08-30
+
+#### In this release we mainly focus on the optimization and stabilization of the framework. 
+#### We also upgrade UIWidgets to version 1.5.4, mainly derived from flutter 1.5.4.
+
+### New Features
+- Optimize the GC performance of the rendering system [\#247](https://github.com/UnityTech/UIWidgets/pull/247)
+- Optimize the rendering performance of shadows [\#257](https://github.com/UnityTech/UIWidgets/pull/257)
+- Leverage Compute Buffer to optimize GPU-CPU communication [\#272](https://github.com/UnityTech/UIWidgets/pull/272)
+- Cupertino Theme Supported [\#287](https://github.com/UnityTech/UIWidgets/pull/287)
+- Support Unity Editor Drag&Drop mouse event [\#253](https://github.com/UnityTech/UIWidgets/pull/253)
+- Implement geometric shapes anti-alias draw [\#262](https://github.com/UnityTech/UIWidgets/pull/262)
+- Optimize paragraph layout [\#254](https://github.com/UnityTech/UIWidgets/pull/254)
+- Support emoji display and edit [\#231](https://github.com/UnityTech/UIWidgets/pull/231)
+