Replace many error string literals with variables existing in
ErrorStrings.h

BUG=:angleproject:1644

Change-Id: If5665a6787a1fa8d789811d774711c3705dfb0ab
Reviewed-on: https://chromium-review.googlesource.com/598588
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>