Line wrap, remove redundancy, and remove 'performant'

[edunham]

182 14:29:00 @jack edunham: larsberg: someone change performant to high-performance or i will die inside

Can't have @metajack dying, inside or out!

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This change is

[edunham]

Old phrasing:

Servo is a modern, performant browser engine designed to be appropriate for applications including embedded use.

New phrasing:

Servo is a modern, high-performance browser engine designed for applications including embedded use.

Servo is a modern, high-performance browser engine designed for both application and embedded use.

[metajack]

how about "design for both applications and embedding". with that or something similar r=me

[edunham]

I think it's correct to phrase "runs in userland" as "designed for application use"?

[edunham]

15:40:00 <@jack> edunham: feel free to correct my grammar if need be :)

Grammar corrected; merging r=jack.