Executed the required changes

Update servo-media. Fixes discarded frames during player setup

Update web-platform-tests to revision 6087baf4a83e7953112242be9fd6e719797ebdf6

Bug 1509027 - Use more restricted scope for Treeherder routes

https://bugzilla.mozilla.org/show_bug.cgi?id=1509027

Cleanup constellation after nll

Use the base Ubuntu distro instead of LinuxMint in './mach bootstrap'

Fixup the issue related with an incorrect distro version string handling

Kill test processes whenever any error occurs

Update web-platform-tests to revision 5349c6a6327372f856ecbe07d863d468a4236726

Minor pull request template cleanup

Introduce NavigationPreloadManager for ServiceWorkerRegistration

Update web-platform-tests to revision 2d5385793ade85b7268ee86db4535a1baeb508ab

Cancel animations that affect nodes that do not participate in layout.

Add a test for dealing with multiple image loading tasks when the list of available images is usable.

Add info about building on Linux Mint to README

Remove redundant `.clone()`s

Update web-platform-tests to revision 912d5081b62d6e6a2f847935c82722e31cca7a1f

Add debug output for webdriver commands.

Delay setting the constellation's active browser id until the context exists.

Add headless support to servodriver harness.

Add automated test for servodriver harness.

Make SSL tests work in servodriver.

performance.rs

Added the specification link

Changed the queue_entry function

PULL_REQUEST_TEMPLATE.md

@@ -2,14 +2,14 @@
 
 
 ---
-<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
+<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
 - [ ] `./mach build -d` does not report any errors
 - [ ] `./mach test-tidy` does not report any errors
-- [ ] These changes fix #__ (github issue number if applicable).
+- [ ] These changes fix #___ (GitHub issue number if applicable)
 
 <!-- Either: -->
 - [ ] There are tests for these changes OR
-- [ ] These changes do not require tests because _____
+- [ ] These changes do not require tests because ___
 
 <!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->
 

README.md

@@ -91,10 +91,12 @@ sudo apt install git curl autoconf libx11-dev \
     libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev libgstreamer-plugins-bad1.0-dev autoconf2.13
 ```
 
-If you using a version prior to **Ubuntu 17.04** or **Debian Sid**, replace `libssl1.0-dev` with `libssl-dev`.
+If you using a version prior to **Ubuntu 17.04**, **Linux Mint 19** or **Debian Sid**, replace `libssl1.0-dev` with `libssl-dev`.
 Additionally, you'll need a local copy of GStreamer with a version later than 12.0. You can place it in `support/linux/gstreamer/gstreamer`, or run `./mach bootstrap-gstreamer` to set it up.
 
-If you are using **Ubuntu 16.04** run `export HARFBUZZ_SYS_NO_PKG_CONFIG=1` before building to avoid an error with harfbuzz.
+If you are using **Ubuntu 16.04** or **Linux Mint 18.*** run `export HARFBUZZ_SYS_NO_PKG_CONFIG=1` before building to avoid an error with harfbuzz.
+
+If you get an undefined symbol error on `gst_player_get_config` try removing `gir1.2-gst-plugins-bad-1.0` and all old versions of clang, see [#22016](https://github.com/servo/servo/issues/22016)
 
 If you are on **Ubuntu 14.04** and encountered errors on installing these dependencies involving `libcheese`, see [#6158](https://github.com/servo/servo/issues/6158) for a workaround. You may also need to install gcc 4.9, clang 4.0, and cmake 3.2: