Auto merge of #24514 - imiklos:webgl_transform_feedback, r=jdm

Add WebGL Transformfeedback support

Reference: https://www.khronos.org/registry/webgl/specs/latest/2.0/#3.7.15
cc @mmatyas @jdm @zakorgy

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components/script/dom/webidls/WebGL2RenderingContext.webidl

@@ -12,9 +12,6 @@ typedef long long GLint64;
 typedef unsigned long long GLuint64;
 
 
-// interface WebGLTransformFeedback : WebGLObject {
-// };
-
 // interface WebGLVertexArrayObject : WebGLObject {
 // };
 
@@ -544,7 +541,7 @@ interface mixin WebGL2RenderingContextBase
   any getSyncParameter(WebGLSync sync, GLenum pname);
 
   /* Transform Feedback */
-  /*WebGLTransformFeedback? createTransformFeedback();
+  WebGLTransformFeedback? createTransformFeedback();
   void deleteTransformFeedback(WebGLTransformFeedback? tf);
   [WebGLHandlesContextLoss] GLboolean isTransformFeedback(WebGLTransformFeedback? tf);
   void bindTransformFeedback (GLenum target, WebGLTransformFeedback? tf);
@@ -553,7 +550,7 @@ interface mixin WebGL2RenderingContextBase
   void transformFeedbackVaryings(WebGLProgram program, sequence<DOMString> varyings, GLenum bufferMode);
   WebGLActiveInfo? getTransformFeedbackVarying(WebGLProgram program, GLuint index);
   void pauseTransformFeedback();
-  void resumeTransformFeedback();*/
+  void resumeTransformFeedback();
 
   /* Uniform Buffer Objects and Transform Feedback Buffers */
   // void bindBufferBase(GLenum target, GLuint index, WebGLBuffer? buffer);

components/script/dom/webidls/WebGLTransformFeedback.webidl

@@ -0,0 +1,11 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+//
+// WebGL IDL definitions scraped from the Khronos specification:
+// https://www.khronos.org/registry/webgl/specs/latest/2.0/#3.7.15
+//
+
+[Exposed=(Window), Pref="dom.webgl2.enabled"]
+interface WebGLTransformFeedback : WebGLObject {
+};