Remove unneeded add_nonglyph_for_char_index

This is a no-op, since a "non-glyph" is simply `GlyphEntry(0)`. This is the
same as `GlyphEntry::initial()`, which all the entries are already initialized
to.

components/gfx/text/glyph.rs

@@ -517,19 +517,6 @@ impl<'a> GlyphStore {
         self.entry_buffer[i.to_usize()] = entry;
     }
 
-    // used when a character index has no associated glyph---for example, a ligature continuation.
-    pub fn add_nonglyph_for_char_index(&mut self,
-                                       i: CharIndex,
-                                       cluster_start: bool,
-                                       ligature_start: bool) {
-        assert!(i < self.char_len());
-
-        let entry = GlyphEntry::complex(cluster_start, ligature_start, 0);
-        debug!("adding spacer for character without associated glyph[idx={:?}]", i);
-
-        self.entry_buffer[i.to_usize()] = entry;
-    }
-
     #[inline]
     pub fn iter_glyphs_for_char_range(&'a self, rang: &Range<CharIndex>) -> GlyphIterator<'a> {
         if rang.begin() >= self.char_len() {

components/gfx/text/shaping/harfbuzz.rs

@@ -435,7 +435,7 @@ impl Shaper {
                 // we'll need to do something special to handle `word-spacing` properly.
                 let character = text[char_byte_span.clone()].chars().next().unwrap();
                 if is_bidi_control(character) {
-                    glyphs.add_nonglyph_for_char_index(char_idx, false, false);
+                    // Don't add any glyphs for bidi control chars
                 } else if character == '\t' {
                     // Treat tabs in pre-formatted text as a fixed number of spaces.
                     //
@@ -476,12 +476,6 @@ impl Shaper {
 
                 // now add the detailed glyph entry.
                 glyphs.add_glyphs_for_char_index(char_idx, &datas);
-
-                // set the other chars, who have no glyphs
-                for _ in text[covered_byte_span].chars().skip(1) {
-                    char_idx = char_idx + char_step;
-                    glyphs.add_nonglyph_for_char_index(char_idx, false, false);
-                }
             }
 
             // shift up our working spans past things we just handled.