Firefox 56.0

What's new in this version:

- Fix up target=_blank links in RDM
- Add extra space around forms to ensure invalid fields are displayed properly
- Remove redundant LegacyExtensionUtils shutdown blocker. The base Extension class now handles adding shutdown blockers and waiting for extension startup before beginning shutdown, so the redundant logic only causes problems.
- Add REX.R mov to the disassembler. To mitigate risk for beta uplift, the logic here is limited to what we need for QueryDosDeviceW on Win7x64. A better long-term fix would be to combine this with the more general mov logic in the REX.W section
- Hook QueryDosDeviceW() in GMP process so it works inside the sandbox. We hook in kernelbase.dll rather than kernel32.dll, as hooking QueryDosDeviceW kernel32.dll is failing on our Win8 tests, it seems because QueryDosDeviceW in kernel32.dll redirects to kernelbase32.dll, and the redirect has insufficient space for our hook in Win8. So hook in kernelbase.dll, where the redirect redirects to instead
- Rename android-api-15 into android-api-16
- Hardcode "proxy" permission string for beta uplift
- Add telemetry probes to measure use of session restore button in tab bar
- Ensure we use the right root element in editor
- Debugger creates an unnecessary breakpoint on reload
- Changes to move to 100% multi on Release 55
- Should not use SOCIAL_ENGINEERING threat type on non-official builds
- Use the correct pref to gate the Application Reputation lists
- Typo preventing locale distribution engines from loading
- Add a new param "buttonAutoFocus" for appUpdater object to focus the button automatically because we need auto focus in about dialog but do not need it in preferences page
- Update MAR to sha384 past 56.0b4 in update-packaging Makefile
- There are some paths to find out if dwrite is enabled, which inits gfxPlatform, which requires information from PopulateScreenInfo, which depends on the refresh driver existing. At this time however, we haven't initialized our vsync source so we crash. This moves vsync initialization earlier in the gfx pipeline
- Handle case where chromeWin.getBrowser() doesn't exist
- Don't rely on gBrowser in nsLoginManagerPrompter. In bug 1266836 we fixed this code to properly work in e10s, but made the mistake of using gBrowser in toolkit code, breaking XUL apps that don't have a gBrowser. This solution implements a different code-path for non-e10s and returns a chrome window for consumers that don't offer a browser
- part2: HTMLEditRules::SplitParagraph() should insert normal <br> element rather than moz-<br> element if split element and/or new element is empty. Currently, HTMLEditRules::SplitParagraph() inserts moz-<br> element when split element and/or new element causes empty line. However, PlaintextSerializer ignores moz-<br> elements. Therefore, empty lines which are created by SplitParagraph() will be removed when it's converted to plaintext. So, it should insert normal <br> element for placeholder of empty lines instead. Note that moz-<br> elements are appeared as normal <br> elements in the result of Element.innerHTML. Additionally, Chromium always inserts a <br> element for empty block elements which are created by Enter key press. Therefore, using normal <br> element in this case shouldn't cause any compatibility problems
- Back out removal of MOZ_PRETTY to build Thunderbird 56 beta
- Backed out changesets 84f048b7dca0 and c261040950bf (bug 1389300) for Stylo svg-as-image reftest failures
- Backed out changeset 554f6e2674fe (bug 1388319)
- Mark ServoStyleSet dirty in its Init
- Remove hide event target flag from accessible when event is dropped
- Don't mix style backend types in nsComputedDOMStyle
- Inherit style backend into NS_NewDOMDocument
- There are some paths to find out if dwrite is enabled, which inits gfxPlatform, which requires information from PopulateScreenInfo, which depends on the refresh driver existing. At this time however, we haven't initialized our vsync source so we crash. This moves vsync initialization earlier in the gfx pipeline.
- Fix xml parsing error
- Preserve array in aria owns hash
- Replace NS_ConvertASCIItoUTF16 by NS_ConvertUTF8toUTF16