layout: Have TextRun::glyph_run_is_preserved_newline take into account TextRunSegment offset (#32119)

A `TextRun` is composed of `TextRunSegment`s that are composed of
`GlyphRun`s.
`TextRun::glyph_run_is_preserved_newline` is indexing into the `TextRun`
text, but the `GlyphRun` indexes that it uses are relative to the
`TextRunSegment`
offset. Before the code was using the offset without incorporating the
`TextRunSegment` offset. This led to miscalculation of preserved newline
location while processing text content.

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components/layout_2020/flow/inline.rs

@@ -2397,7 +2397,7 @@ impl<'a> ContentSizesComputation<'a> {
                         if run.glyph_store.is_whitespace() {
                             // If this run is a forced line break, we *must* break the line
                             // and start measuring from the inline origin once more.
-                            if text_run.glyph_run_is_preserved_newline(run) {
+                            if text_run.glyph_run_is_preserved_newline(segment, run) {
                                 self.forced_line_break();
                                 self.current_line = ContentSizes::zero();
                                 continue;