feat(mock): support mocks via __getPath, __getEvents, and __getDrawCalls

[jtenner]

This is a very large pull request that enables testing canvas context function call events via:

const events = CanvasRenderingContext2D.__getEvents(ctx);
expect(events).toMatchSnapshot();

Please see the following test files to see how to use this feature:

__tests__\classes\CanvasRenderingContext2D.__getDrawCalls.js
__tests__\classes\CanvasRenderingContext2D.__getPath.js
__tests__\classes\CanvasRenderingContext2D.__getEvents.js

closes #33
closes #39
closes #40

[coveralls]

Coverage remained the same at 100.0% when pulling 117670b on mock-support into 829a870 on master.

[coveralls]

Coverage remained the same at 100.0% when pulling 117670b on mock-support into 829a870 on master.

[coveralls]

Coverage remained the same at 100.0% when pulling 117670b on mock-support into 829a870 on master.

[coveralls]

Coverage remained the same at 100.0% when pulling 117670b on mock-support into 829a870 on master.

[coveralls]

Coverage remained the same at 100.0% when pulling 0f133d9 on mock-support into e66874a on master.

[jtenner]

This pull request is big enough, @hustcc should probably check my work before it's pulled.

[hustcc]

@jtenner nice work, If the pr is ready, you can just merge it by yourself. 😄

[jtenner]

Definitely. I'll do this tomorrow.

[jtenner]

I actually need to check that the d.ts file works as intended.

[jtenner]

@hustcc We can release 2.1.0 now. Thanks!