Copy shaders from WR repo.

resources/shaders/ps_rectangle_clip.vs.glsl

@@ -0,0 +1,28 @@
+#line 1
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+struct Rectangle {
+  	PrimitiveInfo info;
+  	vec4 color;
+    Clip clip;
+};
+
+layout(std140) uniform Items {
+    Rectangle rects[WR_MAX_PRIM_ITEMS];
+};
+
+void main(void) {
+    Rectangle rect = rects[gl_InstanceID];
+    VertexInfo vi = write_vertex(rect.info);
+
+    vClipRect = vec4(rect.clip.rect.xy, rect.clip.rect.xy + rect.clip.rect.zw);
+    vClipRadius = vec4(rect.clip.top_left.outer_inner_radius.x,
+                       rect.clip.top_right.outer_inner_radius.x,
+                       rect.clip.bottom_right.outer_inner_radius.x,
+                       rect.clip.bottom_left.outer_inner_radius.x);
+    vPos = vi.local_clamped_pos;
+
+    vColor = rect.color;
+}