Blink's (Chromium) text layout engine works the following way.

1. Layout the entire paragraph of text as a single line.

2. If this doesn't fit into the available width, bisect to the nearest line-break opportunity which might fit.

3. Reshape the text up until this line-break opportunity.

4. If it fits great! If not goto 2.

This converges as it always steps backwards, and avoids the contradictory situations.

Harfbuzz also provides points along the section of text which is safe to reuse, so reshaping typically involes only a small portion of text at the end of the line, if any. https://github.com/harfbuzz/harfbuzz/issues/224

This approach is different to how many text layout engines approach this problem e.g. by adding "one word at a time" to the line, and checking at each stage if it fits.