Close #730

Fix #685

Drop support for older browsers: IE 9-, Android 4, Safari 7-.

Close #676
Close #690
Close #712
Close #723
Fix #718

This commit reverts 8ed3140.

- Update CHANGELOG.md
- Update normalize.css header
- Update package.json

Comment upkeep, per https://bugs.chromium.org/p/chromium/issues/detail?id=376160#c11

- Remove changing the default font family in all browsers.
- Remove the removal of margin on body in all browsers.
- Remove the removal of outline on focused links when they are also
active or hovered in all browsers (opinionated).
- Remove changing the font styles of input controls in all browsers.
- Remove the changing of border, margin, and padding of fieldsets in
all browsers.

Clarification that this rule applies to IE's mobile variant. Interestingly, we'll be able to remove "-ms-text-size-adjust" soon, as Windows Phone 8.1+ supports "-webkit-text-size-adjust" as an alias.

Documentation: https://msdn.microsoft.com/en-us/library/dn793579(v=vs.85).aspx

The results for computed `line-height` in #593 were virtually different in all tested browsers, and since [such browsers are ones we support](https://github.com/necolas/normalize.css#browser-support), I don't see the need to have a *complex* comment naming all of them.

Resolves #581

After modifying search input with -webkit-appearance: textfield, the
focus outline is remaining with `outline-offset: 0`, but should be
`-2px` like other textfield inputs.

Spacing does not need to be normalized for all `input` elements in
Firefox, only `button` and `[type="button"]` elements. These
normalizations were changing the default focus appearance of `input`
elements.

Resolves #549

Correct the text style of placeholders in Chrome, Edge, and Safari

Normalizes placeholder styles in Edge, Chrome, and Safari with Firefox.