Update image.rs

Signed-off-by: Samson <16504129+sagudev@users.noreply.github.com>

Author: sagudev

webrender_api/src/image.rs

@@ -171,6 +171,9 @@ pub enum ImageFormat {
     RGBAI32 = 7,
     /// Four channels, byte storage.
     RGBA8 = 8,
+    
+    /// Four channels, float16 storage.
+    RGBAF16 = 9,
 }
 
 impl ImageFormat {