Changes in 20200621093846

Built from 6803dda74d3349a45d95bc9ce248b90bd9086488

..index..
Bug 1646926 A[Core:Canvas: 2D]Canvas.measureText returns actualBoundingBoxLeft values with wrong sign
Bug 1640900 A[Core:DOM: Selection]Intermittent TEST-UNEXPECTED-PASS | /resize-observer/change-layout-in-error.html | Changing layout in window error handler should not result in lifecyle loop when resize observer loop limit is reached. - expected FAIL
Bug 1646176 R[Core:JavaScript Engine]Fix clang-11 uninitialized warnings in test-prettyprinters.cpp
Bug 1646240 R[Core:Layout]Default to visual direction for text selection in Nightly except Linux
Bug 1645954 R[Core:Layout: Scrolling and Overflow]scrollframe reflow uses stale value of mScrollPort while we are in the process of determining what mScrollPort should be
Bug 1644271 R[Core:Panning and Zooming]Add a pref to always create the MVM, and turn it on
Bug 1646374 R[Core:Panning and Zooming]Ensure scroll restoration works properly with a visual viewport enabled
Bug 1646385 R[Core:Panning and Zooming]Make sure the visual viewport is properly updated when layout scrollbars are added or removed
Bug 1647026 R[DevTools:Console]Array.fill is executed on the array during preview
Bug 1318905 R[Firefox Build System:General]Changes to make SpiderMonkey build on Linux/RISC-V
Bug 1646421 R[Firefox Build System:Lint and Formatting]Update to flake8 3.8.3
Bug 1623024 R[Firefox Build System:Lint and Formatting]mozlint: Evaluate running pylint on the code base
Bug 1646588 R[Firefox Build System:Task Configuration]Taskgraph changes to support esr78
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Changes to 13 bugs - 11 fixed.