[canvaskit] Use linear metrics in shaping demo

Subpixel and slight hinting also make a big difference.

Change-Id: I1b942caf20dbdcf8bebc3504695c673fbe7e4392
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/319791
Reviewed-by: Ben Wagner <bungeman@google.com>

modules/canvaskit/canvaskit/shaping.html

@@ -59,6 +59,10 @@
 
     const textPaint = new CanvasKit.SkPaint();
     const textFont = new CanvasKit.SkFont(typeface, 20);
+    textFont.setLinearMetrics(true);
+    textFont.setSubpixel(true);
+    textFont.setHinting(CanvasKit.FontHinting.Slight);
+
 
     // Only care about these characters for now. If we get any unknown characters, we'll replace
     // them with the first glyph here (the replacement glyph).