style guide tweaks

Most of this is just not mentioning things that need not be mentioned
anymore, but there's one slight style tweak which I think is better,
from

    case Foo: {
        ...
        break;
    }

to

    case Foo: {
        ...
    } break;

which is a little clearer that all paths through case Foo break
when the contents of the {} block become complicated.

Change-Id: Id7fe5ab09437006d125313b07862613316dd403c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/312576
Reviewed-by: Brian Salomon <bsalomon@google.com>
1 file changed