ASTextNode should avoid acquiring its lock multiple times #trivial (T…

…extureGroup#820)

Since the lock was acquire before we try to access the renderer, we should call `-_locked_renderer` to avoid re-acquiring the same (recursive) lock.

Source/ASTextNode.mm

@@ -769,7 +769,7 @@ - (void)_setHighlightRange:(NSRange)highlightRange forAttributeName:(NSString *)
 
       if (highlightTargetLayer != nil) {
         ASDN::MutexLocker l(__instanceLock__);
-        ASTextKitRenderer *renderer = [self _renderer];
+        ASTextKitRenderer *renderer = [self _locked_renderer];
 
         NSArray *highlightRects = [renderer rectsForTextRange:highlightRange measureOption:ASTextKitRendererMeasureOptionBlock];
         NSMutableArray *converted = [NSMutableArray arrayWithCapacity:highlightRects.count];