Auto merge of #13747 - scotttrinh:canvas-webidl, r=Ms2ger

Partial fix for #12415: expose Canvas interfaces

<!-- Please describe your changes on the following line: -->
Fix interface exposure per [the specs](https://html.spec.whatwg.org/multipage/scripting.html#2dcontext).

One lingering question I have is if [`CanvasPath`](https://html.spec.whatwg.org/multipage/scripting.html#canvaspath) needs to be added to `interfaces.worker.js` since it *is* exposed to the `Worker` environment. I tried adding it to the `interfaces.worker.js` list but it failed tests at https://github.com/servo/servo/blob/master/tests/wpt/mozilla/tests/mozilla/interfaces.js#L82

---
<!-- 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 contain a partial fix for #12415 (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [x] These changes do not require tests because _____

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components/script/dom/webidls/CanvasGradient.webidl

@@ -3,7 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // https://html.spec.whatwg.org/multipage/#canvasgradient
-[Exposed=(Window,Worker)]
 interface CanvasGradient {
   // opaque object
   [Throws]

components/script/dom/webidls/CanvasPattern.webidl

@@ -3,8 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // https://html.spec.whatwg.org/multipage/#canvaspattern
-
-[Exposed=(Window,Worker)]
 interface CanvasPattern {
   //void setTransform(SVGMatrix matrix);
 };

components/script/dom/webidls/CanvasRenderingContext2D.webidl

@@ -12,7 +12,6 @@ typedef (HTMLImageElement or
          ImageBitmap */) CanvasImageSource;
 
 //[Constructor(optional unsigned long width, unsigned long height)]
-[Exposed=(Window,Worker)]
 interface CanvasRenderingContext2D {
 
   // back-reference to the canvas
@@ -42,14 +41,14 @@ CanvasRenderingContext2D implements CanvasPathDrawingStyles;
 CanvasRenderingContext2D implements CanvasTextDrawingStyles;
 CanvasRenderingContext2D implements CanvasPath;
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasState {
   // state
   void save(); // push state on state stack
   void restore(); // pop state stack and restore state
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasTransform {
   // transformations (default transform is the identity matrix)
   void scale(unrestricted double x, unrestricted double y);
@@ -73,21 +72,21 @@ interface CanvasTransform {
   void resetTransform();
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasCompositing {
   // compositing
   attribute unrestricted double globalAlpha; // (default 1.0)
   attribute DOMString globalCompositeOperation; // (default source-over)
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasImageSmoothing {
   // image smoothing
   attribute boolean imageSmoothingEnabled; // (default true)
   // attribute ImageSmoothingQuality imageSmoothingQuality; // (default low)
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasFillStrokeStyles {
 
   // colours and styles (see also the CanvasDrawingStyles interface)
@@ -100,7 +99,7 @@ interface CanvasFillStrokeStyles {
   CanvasPattern createPattern(CanvasImageSource image, [TreatNullAs=EmptyString] DOMString repetition);
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasShadowStyles {
   // shadows
   attribute unrestricted double shadowOffsetX; // (default 0)
@@ -109,7 +108,7 @@ interface CanvasShadowStyles {
   attribute DOMString shadowColor; // (default transparent black)
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasRect {
   // rects
   //[LenientFloat]
@@ -120,7 +119,7 @@ interface CanvasRect {
   void strokeRect(unrestricted double x, unrestricted double y, unrestricted double w, unrestricted double h);
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasDrawPath {
   // path API (see also CanvasPathMethods)
   void beginPath();
@@ -143,12 +142,12 @@ interface CanvasDrawPath {
   //boolean isPointInStroke(Path2D path, unrestricted double x, unrestricted double y);
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasUserInterface {
   // TODO?
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasText {
   // text (see also the CanvasDrawingStyles interface)
   //void fillText(DOMString text, unrestricted double x, unrestricted double y,
@@ -158,7 +157,7 @@ interface CanvasText {
   //TextMetrics measureText(DOMString text);
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasDrawImage {
   // drawing images
   [Throws]
@@ -173,7 +172,7 @@ interface CanvasDrawImage {
                                           unrestricted double dw, unrestricted double dh);
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasHitRegion {
   // hit regions
   //void addHitRegion(optional HitRegionOptions options);
@@ -181,7 +180,7 @@ interface CanvasHitRegion {
   //void clearHitRegions();
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasImageData {
   // pixel manipulation
   [Throws]
@@ -206,7 +205,7 @@ enum CanvasTextAlign { "start", "end", "left", "right", "center" };
 enum CanvasTextBaseline { "top", "hanging", "middle", "alphabetic", "ideographic", "bottom" };
 enum CanvasDirection { "ltr", "rtl", "inherit" };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasPathDrawingStyles {
   // line caps/joins
   attribute unrestricted double lineWidth; // (default 1)
@@ -220,7 +219,7 @@ interface CanvasPathDrawingStyles {
   //attribute unrestricted double lineDashOffset;
 };
 
-[NoInterfaceObject, Exposed=(Window,Worker)]
+[NoInterfaceObject]
 interface CanvasTextDrawingStyles {
   // text
   //attribute DOMString font; // (default 10px sans-serif)

components/script/dom/webidls/HTMLCanvasElement.webidl

@@ -5,7 +5,6 @@
 // https://html.spec.whatwg.org/multipage/#htmlcanvaselement
 typedef (CanvasRenderingContext2D or WebGLRenderingContext) RenderingContext;
 
-[Exposed=(Window,Worker)]
 interface HTMLCanvasElement : HTMLElement {
   [Pure]
            attribute unsigned long width;