Bug 1559276 - Part 2: Retire the support for 3-valued syntax for posi…

…tion. r=emilio

According to this resolved spec issue:
w3c/csswg-drafts#2140,
we retire the 3-valued <position> on
1. `object-position`
2. `perspective-origin`,
3. `mask-position`
4. `circle()` and `ellipse()`
, but still keep the support for `background-position`.

Besides, I simply run this python script to generate the .ini file:
```
s = sys.argv[1] + ".ini"
with open(s, "w") as f:
    f.write('[{}]\n'.format(sys.argv[1]))
    f.write('  expected: FAIL\n')
    f.write('  bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1559276\n')
```

Differential Revision: https://phabricator.services.mozilla.com/D37126

UltraBlame original commit: 6ec2809da4e31720cbb59b4ba71616c1c168553e

layout/style/test/property_database.js

@@ -2557,54 +2557,6 @@ blue
 "
 /
 /
-FIXME
-(
-emilio
-)
-:
-We
-should
-not
-be
-allowing
-3
--
-value
-positions
-anywhere
-else
-/
-/
-than
-on
-background
--
-position
-see
-/
-/
-https
-:
-/
-/
-github
-.
-com
-/
-w3c
-/
-csswg
--
-drafts
-/
-issues
-/
-2140
-.
-/
-/
-/
-/
 When
 that
 happens
@@ -2630,6 +2582,7 @@ closest
 side
 at
 left
+0px
 bottom
 7in
 hsl
@@ -9173,6 +9126,7 @@ circle
 (
 at
 top
+0px
 left
 20px
 )
@@ -9307,6 +9261,7 @@ ellipse
 (
 at
 top
+0px
 left
 20px
 )
@@ -10004,6 +9959,15 @@ rubbish
 )
 "
 "
+circle
+(
+at
+top
+left
+20px
+)
+"
+"
 ellipse
 (
 at
@@ -10107,6 +10071,15 @@ rubbish
 )
 "
 "
+ellipse
+(
+at
+top
+left
+20px
+)
+"
+"
 polygon
 (
 at
@@ -27421,12 +27394,6 @@ left
 "
 "
 top
-0
-%
-left
-"
-"
-top
 left
 "
 "
@@ -27776,16 +27743,6 @@ top
 "
 "
 left
-top
-15px
-"
-"
-left
-10px
-top
-"
-"
-left
 20
 %
 "
@@ -27894,6 +27851,16 @@ calc
 rubbish
 )
 "
+"
+left
+top
+15px
+"
+"
+left
+10px
+top
+"
 ]
 }
 "
@@ -33276,6 +33243,7 @@ calc
 "
 bottom
 right
+8px
 scroll
 none
 transparent
@@ -49924,16 +49892,6 @@ top
 "
 "
 left
-top
-15px
-"
-"
-left
-10px
-top
-"
-"
-left
 20
 %
 "
@@ -50019,6 +49977,16 @@ left
 20
 20
 "
+"
+left
+top
+15px
+"
+"
+left
+10px
+top
+"
 ]
 }
 opacity

servo/components/style/properties/shorthands/background.mako.rs

@@ -255,6 +255,7 @@ specified
 :
 :
 {
+AllowQuirks
 Color
 Position
 PositionComponent
@@ -683,14 +684,20 @@ try
 |
 input
 |
+{
 Position
 :
 :
-parse
+parse_three_value_quirky
 (
 context
 input
+AllowQuirks
+:
+:
+No
 )
+}
 )
 {
 position
@@ -1818,7 +1825,7 @@ value
 Position
 :
 :
-parse_quirky
+parse_three_value_quirky
 (
 context
 input