Bug 1622138 [wpt PR 22230] - Make computedStyleMap return the compute…

…d value for lineHeight, a=testonly

Automatic update from web-platform-tests
Make computedStyleMap return the computed value for lineHeight

It previously returned the resolved value as produced by
ValueForLineHeight (this property is unique in that the computed and
resolved values differ even without a layout object).
Introduce another serializer ComputedValueForLineHeight which produces
the actual computed value.

Change-Id: Ic27d9a4fe7c67cbbb577ec4e4efed14a88a846c9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2101858
Reviewed-by: Rune Lillesveen <futharkchromium.org>
Commit-Queue: George Steel <gtsteelchromium.org>
Cr-Commit-Position: refs/heads/master{#750170}

--

wpt-commits: 550ffc84d3c79e80ea4b8b90a2489a0b8426aa1b
wpt-pr: 22230

UltraBlame original commit: 42881b0536f855b7d1c08017dbbc37f120502315

testing/web-platform/tests/css/css-typed-om/the-stylepropertymap/properties/line-height.html

@@ -301,7 +301,7 @@
 assert_is_unit
 (
 '
-px
+number
 '
 result
 )