Do not mark the first glyph as unsafe to break

Fixes #791.

src/hb-buffer-private.hh

@@ -344,8 +344,7 @@ struct hb_buffer_t {
   inline void
   unsafe_to_break_all (void)
   {
-    for (unsigned int i = 0; i < len; i++)
-      info[i].mask |= HB_GLYPH_FLAG_UNSAFE_TO_BREAK;
+    unsafe_to_break_impl (0, len);
   }
   inline void
   safe_to_break_all (void)

src/hb-coretext.cc

@@ -1244,8 +1244,6 @@ resize_and_retry:
 	pos->x_offset = info->var1.i32;
 	pos->y_offset = info->var2.i32;
 
-	info->mask = HB_GLYPH_FLAG_UNSAFE_TO_BREAK;
-
 	info++, pos++;
       }
     else
@@ -1255,8 +1253,6 @@ resize_and_retry:
 	pos->x_offset = info->var1.i32;
 	pos->y_offset = info->var2.i32;
 
-	info->mask = HB_GLYPH_FLAG_UNSAFE_TO_BREAK;
-
 	info++, pos++;
       }
 

src/hb-directwrite.cc

@@ -878,8 +878,6 @@ retry_getglyphs:
     pos->x_offset =
       x_mult * (isRightToLeft ? -info->var1.i32 : info->var1.i32);
     pos->y_offset = y_mult * info->var2.i32;
-
-    info->mask = HB_GLYPH_FLAG_UNSAFE_TO_BREAK;
   }
 
   if (isRightToLeft)

src/hb-graphite2.cc

@@ -360,7 +360,6 @@ _hb_graphite2_shape (hb_shape_plan_t    *shape_plan,
       hb_glyph_info_t *info = &buffer->info[clusters[i].base_glyph + j];
       info->codepoint = gids[clusters[i].base_glyph + j];
       info->cluster = clusters[i].cluster;
-      info->mask = HB_GLYPH_FLAG_UNSAFE_TO_BREAK;
       info->var1.i32 = clusters[i].advance;     // all glyphs in the cluster get the same advance
     }
   }

src/hb-uniscribe.cc

@@ -1025,8 +1025,6 @@ retry:
     pos->x_advance = x_mult * (int32_t) info->mask;
     pos->x_offset = x_mult * (backward ? -info->var1.i32 : info->var1.i32);
     pos->y_offset = y_mult * info->var2.i32;
-
-    info->mask = HB_GLYPH_FLAG_UNSAFE_TO_BREAK;
   }
 
   if (backward)