Use iterators to make some logic clearer
Use Option functions to make logic clearer
Make move mutation out of compute_minimum_ascent_and_descent
Remove some unnecessary mutable references
Use Option::expect instead of pattern matching in try_append_to_line_by_new_line
Clean up skip_while iteration
Separate "desktop" and "mobile" zoom calculations.

This ensures that the layout viewport responds to each type of zoom correctly,
and lays the ground for CSS Media Queries and CSS Device Adaption.

Until we have proper touch support, mobile-style "pinch" zoom can be simulated
by holding Ctrl while scrolling with a mousewheel or trackpad gesture.
Revert "Revert "Merge pull request #2609 from brson/parallel-render""

This reverts commit 3f8f065b76d034803bfb666899ef07afce0a1cd9.
gfx: Don't crash if there is no graphics metadata.
recompile servo when modifying the user-agent style sheet
do not display noscript element
adding test for noscript
Merge pull request #2687 from pcwalton/parallel-render

Parallel render
Merge pull request #2666 from mbrubeck/pinch

Separate "desktop" and "mobile" zoom calculations.
Merge pull request #2682 from bjz/assorted-cleanups

Assorted cleanups in gfx and layout
Merge pull request #2688 from schaars/noscript

Do not display noscript element