Guideline for feature IDs for interfaces and methods

[foolip]

We currently have a mix of two styles for features named after interfaces or methods.

All as one word:

• CloseWatcher → "closewatcher"
• getHTML() → "gethtml"
• requestIdleCallback() → "requestidlecallback"

Hyphenated:

• EditContext → "edit-context"
• getComputedStyle() → "get-computed-style"
• requestVideoFrameCallback() → "request-video-frame-callback"

I think we should bless one style.

[foolip]

BigInt64Array is an awkward case if we wanted to always hyphenate. big-int64-array???

If removing hyphens, OES_texture_half_float_linear and other WebGL extensions are a challenge. oestexturehalffloatlinear is a bit too novel IMHO, not an improvement.