Update fill and stroke style only when required

So far fill and stroke style updates have been sent to the canvas paint
thread by `SetFillStyle()` and `SetStrokeStyle()`. This resulted in
fill/stroke style updates not being considered by the canvas paint
thread between the latest call of `SetFillStyle()`/`SetStrokeStyle()` and
the drawing operation (e.g. fill or stroke).

This issue is solved by making `SetFillStyle()` and `SetStrokeStyle()`
update the local canvas state and propagating the state to the canvas
paint thread right before any drawing operation that requires it.

tests/wpt/metadata/2dcontext/fill-and-stroke-styles/2d.gradient.object.update.html.ini

@@ -1,5 +0,0 @@
-[2d.gradient.object.update.html]
-  type: testharness
-  [Canvas test: 2d.gradient.object.update]
-    expected: FAIL
-

tests/wpt/metadata/2dcontext/fill-and-stroke-styles/2d.pattern.animated.gif.html.ini

@@ -1,4 +0,0 @@
-[2d.pattern.animated.gif.html]
-  [createPattern() of an animated GIF draws the first frame]
-    expected: FAIL
-

tests/wpt/metadata/offscreen-canvas/fill-and-stroke-styles/2d.gradient.object.update.html.ini

@@ -1,4 +0,0 @@
-[2d.gradient.object.update.html]
-  [OffscreenCanvas test: 2d.gradient.object.update]
-    expected: FAIL
-

tests/wpt/metadata/offscreen-canvas/fill-and-stroke-styles/2d.gradient.object.update.worker.js.ini

@@ -1,4 +0,0 @@
-[2d.gradient.object.update.worker.html]
-  [2d]
-    expected: FAIL
-