layout: Set baseline even if line box has no fragment (#39235)

`InlineFormattingContextLayout::finish_current_line_and_reset()` has an
early return in case the line has no fragment. However, if the line only
has a forced line break, then we still need to set the baseline.

Testing: Adding new test.

Signed-off-by: Oriol Brufau <obrufau@igalia.com>

tests/wpt/meta/MANIFEST.json

@@ -118917,6 +118917,19 @@
         {}
        ]
       ],
+      "inline-block-baseline-016.html": [
+       "c4efa04d4a66ea59d55888a1b5d175b1da7660ef",
+       [
+        null,
+        [
+         [
+          "/css/reference/ref-filled-green-200px-square.html",
+          "=="
+         ]
+        ],
+        {}
+       ]
+      ],
       "line-height-201.html": [
        "00ab2aa52755d27c5bbd3b41d91a6f8e138c2899",
        [