Update rust-cssparser to 0.20.2.
This reduces memory consumption of list-valued properties in the common case of one entry in the list.
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TEST: fix and add case of po-observe.any.js
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1. implementing step 3 from the [`PerformanceObserver.observe()`](https://w3c.github.io/performance-timeline/#dom-performanceobserver-observe()) method spec properly.
2. also add cases about step 1 & 2
work on the top of #18283
r? @ferjm
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Bug 1395064 - stylo: Add uses of fallible Vec, SmallVec and HashMap f…
…acilities. r=emilio@crisal.io.
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update mach.bat if use VS buildtool for Windows build
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Add path in `mach.bat`. If user only install VS buildtool, they now can use `mach.bat`
And therefore modify `README`
Continue to PR #18145
r? @larsbergstrom
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Shrink the storage needed by specified background images
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This makes a specified background image take 48 bytes instead of 1024 bytes.
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style: remove selector_map::find_push.
It has a single caller and is overly generic, which is going to make harder to
add fallible allocations to it.
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