Try to get LayoutUnit.h compiling on clang/win bots after VS2015 switch.
Try to get LayoutUnit.h compiling on clang/win bots after VS2015 switch.

BUG=82385,498544
TBR=brucedawson@chromium.org

Review URL: https://codereview.chromium.org/1675803004 .

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#374008}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk