Merge branch 'double_to_float' into 'master'

Double to float

See merge request upm-packages/ui-widgets/com.unity.uiwidgets!70

README.md

 3. **Refine Code Style Rules**: Edit the ".editorconfig" file under \<YourProjectPath\>/Packages/com.unity.uiwidgets/". Visit
  https://www.jetbrains.com/help/rider/EditorConfig_Index.html for the detailed.
 
+#### Generate njk Code
+
+1. **Go to scripts Folder and Run npm install**:
+```
+cd <YourProjectPath>/Packages/com.unity.uiwidgets/scripts
+npm install
+```
+
+2. **Run the codegen Command**:
+```
+node uiwidgets-cli.js codegen . generate mixin code
+```

Runtime/rendering/box.mixin.gen.cs

-using System;
 using System.Collections.Generic;
 using Unity.UIWidgets.gestures;
 using Unity.UIWidgets.ui;

Runtime/rendering/proxy_box.mixin.njk

                 return this.child.getMinIntrinsicWidth(height);
             }
 
-            return 0.0;
+            return 0.0f;
         }
 
         protected override float computeMaxIntrinsicWidth(float height) {
 
-            return 0.0;
+            return 0.0f;
         }
 
         protected override float computeMinIntrinsicHeight(float width) {
 
-            return 0.0;
+            return 0.0f;
         }
 
         protected override float computeMaxIntrinsicHeight(float width) {
 
-            return 0.0;
+            return 0.0f;
         }
 
         protected override float? computeDistanceToActualBaseline(TextBaseline baseline) {