Fix vertical alignment at the root of an IFC (#31636)

At the root of an inline formatting context, we used its vertical-align
in order to compute the strut. That was wrong, since vertical-align
on a block container shouldn't affect the contents, it should only
affect the alignment of the block container (if it's inline-level)
within the parent IFC.

This was only working well if the block container was block-level, since
effective_vertical_align_for_inline_layout returned `baseline` for
block-level boxes.

Instead of the outer display type, this patch changes the logic to check
whether we are at the root of the IFC.

tests/wpt/meta/MANIFEST.json

@@ -63058,6 +63058,19 @@
         {}
        ]
       ],
+      "vertical-align-122.xht": [
+       "1d7c180f197b9262dd98aa162595b3eb914f60d1",
+       [
+        null,
+        [
+         [
+          "/css/CSS2/linebox/vertical-align-122-ref.xht",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
       "vertical-align-applies-to-001.xht": [
        "fca1480f7367209223f370ff01acbc45ef7b3778",
        [
@@ -371510,6 +371523,10 @@
        "c0db9e0e8bbc2bbec91ffaa564e326b4744dd2fd",
        []
       ],
+      "vertical-align-122-ref.xht": [
+       "86b4856266285a3a9b66b5c426384d2699cbaceb",
+       []
+      ],
       "vertical-align-applies-to-001-ref.xht": [
        "8ed51e0c21a0613e67c49e3e36e488e176027165",
        []

tests/wpt/meta/css/CSS2/linebox/inline-formatting-context-011.xht.ini

@@ -1,2 +0,0 @@
-[inline-formatting-context-011.xht]
-  expected: FAIL