Fix VariableBlurStyleTests compile issue

Author: Kyle-Ye

Tests/OpenSwiftUICoreTests/Graphic/VariableBlurStyleTests.swift

@@ -6,6 +6,12 @@ import OpenSwiftUICore
 import OpenSwiftUITestsSupport
 import Testing
 
+extension GraphicsImage {
+    fileprivate static var empty: GraphicsImage {
+        self.init(contents: nil, scale: 1, unrotatedPixelSize: .zero, orientation: .up, isTemplate: false)
+    }
+}
+
 struct VariableBlurStyleTests {
     @Test
     func variableBlurStyleInit() {
@@ -27,7 +33,7 @@ struct VariableBlurStyleTests {
         let style3 = VariableBlurStyle(radius: 10, mask: .none)
         #expect(style3.isIdentity == true)
 
-        let style4 = VariableBlurStyle(radius: 10, mask: .image(GraphicsImage()))
+        let style4 = VariableBlurStyle(radius: 10, mask: .image(.empty))
         #expect(style4.isIdentity == false)
     }
 
@@ -63,9 +69,9 @@ struct VariableBlurStyleTests {
     func variableBlurStyleMaskEquality() {
         let mask1 = VariableBlurStyle.Mask.none
         let mask2 = VariableBlurStyle.Mask.none
-        let mask3 = VariableBlurStyle.Mask.image(GraphicsImage())
-        let mask4 = VariableBlurStyle.Mask.image(GraphicsImage())
-        
+        let mask3 = VariableBlurStyle.Mask.image(.empty)
+        let mask4 = VariableBlurStyle.Mask.image(.empty)
+
         #expect(mask1 == mask2)
         #expect(mask3 == mask4)
         #expect(mask1 != mask3)
@@ -80,7 +86,7 @@ struct VariableBlurStyleTests {
             (VariableBlurStyle(radius: 10.0, isOpaque: true), "0d0000204110012200"),
             (VariableBlurStyle(radius: 10.0, isOpaque: true, dither: true), "0d00002041100118012200"),
             (VariableBlurStyle(radius: 10.0, isOpaque: false, dither: true, mask: .none), "0d0000204118012200"),
-            (VariableBlurStyle(radius: 10.0, mask: .image(GraphicsImage())), "0d0000204122020a00"),
+            (VariableBlurStyle(radius: 10.0, mask: .image(.empty)), "0d0000204122020a00"),
         ]
     )
     func pbMessage(style: VariableBlurStyle, hexString: String) throws {
@@ -91,7 +97,7 @@ struct VariableBlurStyleTests {
     @Test(
         arguments: [
             (VariableBlurStyle.Mask.none, ""),
-            (VariableBlurStyle.Mask.image(GraphicsImage()), "0a00"),
+            (VariableBlurStyle.Mask.image(.empty), "0a00"),
         ]
     )
     func maskPBMessage(mask: VariableBlurStyle.Mask, hexString: String) throws {