Disable hyphenation when word overlaps style boundary

In cases when a word (as defined by the ICU break iterator) overlaps a
style boundary, the returned wordStart can be extend before the range
currently being measured for layout. When we try to hyphenate the
resulting substrings, we get a negative range, which crashes. This
patch disables hyphenation in this case.

Bug: 27237112
Change-Id: I76d04b39dd3b4d6d267aaaf4bebc9ab361891646

engine/src/flutter/libs/minikin/LineBreaker.cpp

@@ -174,7 +174,8 @@ float LineBreaker::addStyleRun(MinikinPaint* paint, const FontCollection* typefa
             if (paint != nullptr && mHyphenator != nullptr &&
                     mHyphenationFrequency != kHyphenationFrequency_None &&
                     !wordEndsInHyphen && !temporarilySkipHyphenation &&
-                    wordEnd > wordStart && wordEnd - wordStart <= LONGEST_HYPHENATED_WORD) {
+                    wordStart >= start && wordEnd > wordStart &&
+                    wordEnd - wordStart <= LONGEST_HYPHENATED_WORD) {
                 mHyphenator->hyphenate(&mHyphBuf, &mTextBuf[wordStart], wordEnd - wordStart);
 #if VERBOSE_DEBUG
                 std::string hyphenatedString;