Fine-tune fake-bolding condition

The old logic for fake bolding results in no fake bolding for a bold
span on a light weight (300) because the target weight (600 in this
case) didn't meet the condition. This patch fine-tunes the threshold
to enable fake bolding for this.

Bug: 17587185

Change-Id: I04abd00a74240cbed79c417f81486aa2158b2806

libs/minikin/FontFamily.cpp

@@ -141,11 +141,11 @@ static int computeMatch(FontStyle style1, FontStyle style2) {
 }
 
 static FontFakery computeFakery(FontStyle wanted, FontStyle actual) {
-    // If desired weight is bold or darker, and 2 or more grades higher
-    // than actual (for example, medium 500 -> bold 700), then select
-    // fake bold.
+    // If desired weight is semibold or darker, and 2 or more grades
+    // higher than actual (for example, medium 500 -> bold 700), then
+    // select fake bold.
     int wantedWeight = wanted.getWeight();
-    bool isFakeBold = wantedWeight >= 7 && (wantedWeight - actual.getWeight()) >= 2;
+    bool isFakeBold = wantedWeight >= 6 && (wantedWeight - actual.getWeight()) >= 2;
     bool isFakeItalic = wanted.getItalic() && !actual.getItalic();
     return FontFakery(isFakeBold, isFakeItalic);
 }