[morx] Fix MORX-35

Fixes https://github.com/harfbuzz/harfbuzz/issues/1224

src/hb-aat-layout-morx-table.hh

@@ -661,11 +661,17 @@ struct InsertionSubtable
 	 * current glyph, the next glyph processed would in fact be the first
 	 * one inserted."
 	 *
-	 * This suggests that if DontAdvance is NOT set, we should move to
-	 * end+count.  If it *was*, then move to end, such that newly inserted
-	 * glyphs are now visible.
+	 * So, if DontAdvance *is* set, we move to "end", such that newly
+	 * inserted glyphs are visible.
+	 *
+	 * If DontAdvance is *not* set, if inserted before, move past them,
+	 * such that original current glyph will be skipped over by the driver.
+	 * Otherwise, again, just move to "end" such that current glyph will
+	 * be skipped over by driver.
+	 *
+	 * https://github.com/harfbuzz/harfbuzz/issues/1224
 	 */
-	buffer->move_to ((flags & DontAdvance) ? end : end + count);
+	buffer->move_to ((flags & DontAdvance) || !before ? end : end + count);
       }
 
       if (flags & SetMark)

test/shaping/data/text-rendering-tests/DISABLED

@@ -1,6 +1,3 @@
-# https://github.com/harfbuzz/harfbuzz/issues/1224
-tests/MORX-35.tests
-
 # Non-Unicode cmap
 tests/CMAP-3.tests
 

test/shaping/data/text-rendering-tests/Makefile.sources

@@ -55,6 +55,7 @@ TESTS = \
 	tests/MORX-32.tests \
 	tests/MORX-33.tests \
 	tests/MORX-34.tests \
+	tests/MORX-35.tests \
 	tests/MORX-36.tests \
 	tests/MORX-37.tests \
 	tests/MORX-38.tests \
@@ -73,7 +74,6 @@ TESTS = \
 
 DISBALED_TESTS = \
 	tests/CMAP-3.tests \
-	tests/MORX-35.tests \
 	tests/SHARAN-1.tests \
 	tests/SHBALI-1.tests \
 	tests/SHBALI-2.tests \