Changes in 20200504093644

Built from 8e4a846c1c5bdb6f5c1d871b4d0e826a2a09b79e

..index..
Bug 1625745 R[Core:CSS Parsing and Computation]Convert counter-system #defines to enum classes.
Bug 1633863 R[Core:CSS Parsing and Computation]Remove nsCSSProps' dependence on BoolVarCache
Bug 1634270 R[Core:DOM: Security]Fix rebase error from Bug 1623565 affecting MixedContentBlocker
Bug 1632259 R[Core:Graphics]Refactor WebRender configuration logic in gfxPlatform to be testable
Bug 1630125 R[Core:ImageLib]Intermittent TEST-UNEXPECTED-PASS | image/test/reftest/bmp/bmpsuite/q/rgb24prof2.bmp == image/test/reftest/bmp/bmpsuite/q/rgb24.png | image comparison, max difference: 10, number of differing pixels: 6590
Bug 1634732 R[Core:Internationalization]nulling out the link in Document::LocalizationLinkRemoved is not sound if we're blocking the load event
Bug 1620646 A[Core:JavaScript Engine]Fix mixed `' ticks in "debuggee would run" warning
Bug 1633732 R[Core:Layout: Block and Inline]Intermittent first-letter/23605-5.html == first-letter/23605-5-ref.html | image comparison, max difference: 63, number of differing pixels: 1
Bug 1633276 A[Core:Web Painting]Transition of opacity not smooth
Bug 1625803 R[Core:WebRTC: Networking]Enable transport-cc extension by default
Bug 1581383 R[Firefox:Preferences]Labeling of default app handling in preferences is confusing for PDF files
Bug 1634050 R[Firefox Build System:Source Code Analysis][clang-format] When analyzing files outside of the tree take along the appropriate `.clang-format` file as well
Bug 1560218 R[WebExtensions:Frontend][WebExtensions] Add the ability to duplicate tab to a specified index
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Changes to 13 bugs - 11 fixed.