Auto merge of #13493 - scotttrinh:webgl-idl, r=jdm

Partial fix for #12415: expose WebGL interfaces

<!-- Please describe your changes on the following line: -->

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes partially fix #12415  (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [X] These changes do not require tests because they do not add any features

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/13493)
<!-- Reviewable:end -->

components/script/dom/webidls/WebGLRenderingContext.webidl

@@ -41,7 +41,7 @@ dictionary WebGLContextAttributes {
     GLboolean failIfMajorPerformanceCaveat = false;
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface WebGLRenderingContextBase
 {
 
@@ -762,7 +762,6 @@ interface WebGLRenderingContextBase
     void viewport(GLint x, GLint y, GLsizei width, GLsizei height);
 };
 
-[Exposed=(Window,Worker)]
 interface WebGLRenderingContext
 {
 };