Auto merge of #26697 - utsavoza:ugo/issue-11681/22-05-2020, r=jdm

Implement CanvasRenderingContext2d.fillText

The PR consists of broadly two main changes:
- Implementation of Canvas2dRenderingContext.font
- Basic implementation of Canvas2dRenderingContext.fillText

Although I am not fully sure about the long term goals for the canvas backend in Servo, I assumed limited scope for font and text handling (should support simple text drawing with font selection) in the current implementation as I believe a more complete implementation would eventually be brought in as a part of #22957.

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #11681
- [x] There are tests for these changes

Cargo.lock

@@ -504,6 +504,8 @@ dependencies = [
  "cssparser",
  "euclid",
  "fnv",
+ "font-kit",
+ "gfx",
  "gleam 0.11.0",
  "half",
  "ipc-channel",
@@ -512,8 +514,10 @@ dependencies = [
  "num-traits",
  "pixels",
  "raqote",
+ "servo_arc",
  "servo_config",
  "sparkle",
+ "style",
  "surfman",
  "surfman-chains",
  "surfman-chains-api",
@@ -541,6 +545,7 @@ dependencies = [
  "serde_bytes",
  "servo_config",
  "sparkle",
+ "style",
  "time",
  "webrender_api",
  "webxr-api",
@@ -5429,6 +5434,7 @@ dependencies = [
  "encoding_rs",
  "euclid",
  "fallible",
+ "font-kit",
  "fxhash",
  "hashglobe",
  "html5ever",