Make more functions const

Make more functions const
https://bugs.webkit.org/show_bug.cgi?id=117455

Reviewed by Benjamin Poulain.

Merge https://chromium.googlesource.com/chromium/blink/+/886866f5034d7f30f8aa607b909313f99db1f3b4.

* editing/VisibleUnits.cpp:
(WebCore::CachedLogicallyOrderedLeafBoxes::boxIndexInLeaves):
* html/canvas/WebGLRenderingContext.cpp:
* page/ContentSecurityPolicy.cpp:
(WebCore::CSPDirectiveList::evalDisabledErrorMessage):
* rendering/RenderBlockLineLayout.cpp:
(WebCore::LineWidth::shouldIndentText):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@151415 268f45cc-cd09-0410-ab3c-d52691b4dbfc