Auto merge of #12873 - shinglyu:abs-margin-patch, r=notriddle,emilio

Fix absolute-flow's auto positioning

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If an absolute positioned flow has no top, bottom, left, right property, its hypothetical box position should be the margin-end of its previous sibling, not the border-end.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #12676 (github issue number if applicable).

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- [x] There are tests for these changes

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tests/wpt/metadata-css/css-transforms-1_dev/html/perspective-origin-001.htm.ini

@@ -1,3 +0,0 @@
-[perspective-origin-001.htm]
-  type: reftest
-  expected: FAIL

tests/wpt/metadata-css/css-transforms-1_dev/html/perspective-origin-002.htm.ini

@@ -1,3 +0,0 @@
-[perspective-origin-002.htm]
-  type: reftest
-  expected: FAIL

tests/wpt/metadata-css/css-transforms-1_dev/html/perspective-origin-003.htm.ini

@@ -1,3 +0,0 @@
-[perspective-origin-003.htm]
-  type: reftest
-  expected: FAIL

tests/wpt/metadata-css/css-transforms-1_dev/html/perspective-origin-004.htm.ini

@@ -1,3 +0,0 @@
-[perspective-origin-004.htm]
-  type: reftest
-  expected: FAIL

tests/wpt/metadata-css/css-transforms-1_dev/html/perspective-origin-005.htm.ini

@@ -1,3 +0,0 @@
-[perspective-origin-005.htm]
-  type: reftest
-  expected: FAIL

tests/wpt/metadata-css/css-transforms-1_dev/html/perspective-origin-006.htm.ini

@@ -1,3 +0,0 @@
-[perspective-origin-006.htm]
-  type: reftest
-  expected: FAIL

tests/wpt/metadata-css/css-transforms-1_dev/html/scalex.htm.ini

@@ -1,3 +0,0 @@
-[scalex.htm]
-  type: reftest
-  expected: FAIL