Update WR (CPU text optimizations, image format renames).

[glennw]

This change is 

[highfive]

Heads up! This PR modifies the following files:

• @KiChjang: components/script/dom/canvasrenderingcontext2d.rs, components/net/image_cache.rs, components/net_traits/image/base.rs, components/net_traits/image/base.rs, components/script/dom/webglrenderingcontext.rs and 1 more
• @fitzgen: components/script/dom/canvasrenderingcontext2d.rs, components/script/dom/webglrenderingcontext.rs, components/script/dom/paintworkletglobalscope.rs
• @emilio: components/layout/display_list_builder.rs, components/canvas/webgl_paint_thread.rs, components/script/dom/webglrenderingcontext.rs

[highfive]

Warning

• These commits modify net, layout, and script code, but no tests are modified. Please consider adding a test!

[glennw]

r? anyone

[glennw]

@Eijebong FYI, this PR brings WR up to date in Servo. In case it doesn't land before your serde 1.0 changes are ready to go, you can use this as a base for the required WR API changes.

[emilio]

Looks good, though I'd expect some WebGL tests to fail... Let's see.

@bors-servo r+

[bors-servo]

📌 Commit e7b1e04 has been approved by emilio

[glennw]

@emilio Tests should be OK - it's just a rename of the format to match the actual layout. There's no actual byte ordering changes.

[bors-servo]

⌛ Testing commit e7b1e04 with merge e1bce24...

[bors-servo]

☀️ Test successful - android, arm32, arm64, linux-dev, linux-rel-css, linux-rel-wpt, mac-dev-unit, mac-rel-css1, mac-rel-css2, mac-rel-wpt1, mac-rel-wpt2, mac-rel-wpt3, mac-rel-wpt4, windows-msvc-dev
Approved by: emilio
Pushing e1bce24 to master...