Fix Bug 993709 - Improve font selection for Simplified Chinese (zh-CN)

And removed unnecessary comments in zh-TW.

media/css/l10n/zh-CN/intl.css

@@ -1,3 +1,41 @@
+/* Bug 993709 */
+
+@font-face {
+  font-family: X-LocaleSpecific;
+  font-weight: normal;
+  src: /* OS X */
+       local(FZLTXHK--GBK1-0), /* = Lantinghei SC Extralight */
+       local(HiraginoSansGB-W3),
+       /* Windows */
+       local('Microsoft YaHei Light'),
+       /* Linux */
+       local(DroidSansFallbackFull);
+}
+
+@font-face {
+  font-family: X-LocaleSpecific;
+  font-weight: bold;
+  src: /* OS X */
+       local(FZLTZHK--GBK1-0), /* = Lantinghei SC Demibold */
+       local(HiraginoSansGB-W6),
+       /* Windows */
+       local('Microsoft YaHei Bold'),
+       /* Linux */
+       local(DroidSansFallbackFull);
+}
+
+@font-face {
+  font-family: X-LocaleSpecific-Extrabold;
+  font-weight: 800;
+  src: /* OS X */
+       local(FZLTTHK--GBK1-0), /* = Lantinghei SC Heavy */
+       local(HiraginoSansGB-W6),
+       /* Windows */
+       local('Microsoft YaHei Bold'),
+       /* Linux */
+       local(DroidSansFallbackFull);
+}
+
 /* Bug 973171 */
 
 * {

media/css/l10n/zh-TW/intl.css

@@ -3,43 +3,34 @@
 @font-face {
   font-family: X-LocaleSpecific;
   font-weight: normal;
-  src: /* All */
-       /* OS X */
+  src: /* OS X */
        local(FZLTXHB--B51-0), /* = Lantinghei TC Extralight */
        /* Windows */
        local('Microsoft JhengHei Light'),
        /* Linux */
-       local(DroidSansFallbackFull)
-       /* Android */
-       ;
+       local(DroidSansFallbackFull);
 }
 
 @font-face {
   font-family: X-LocaleSpecific;
   font-weight: bold;
-  src: /* All */
-       /* OS X */
+  src: /* OS X */
        local(FZLTZHB--B51-0), /* = Lantinghei TC Demibold */
        /* Windows */
        local('Microsoft JhengHei Bold'),
        /* Linux */
-       local(DroidSansFallbackFull)
-       /* Android */
-       ;
+       local(DroidSansFallbackFull);
 }
 
 @font-face {
   font-family: X-LocaleSpecific-Extrabold;
   font-weight: 800;
-  src: /* All */
-       /* OS X */
+  src: /* OS X */
        local(FZLTTHB--B51-0), /* = Lantinghei TC Heavy */
        /* Windows */
        local('Microsoft JhengHei Bold'),
        /* Linux */
-       local(DroidSansFallbackFull)
-       /* Android */
-       ;
+       local(DroidSansFallbackFull);
 }
 
 /* Bug 973171 */