See #290 - allows font-weight overriding.

Why:

* Another step to move away from aggressive merging.

lib/properties/compactable.js

@@ -125,6 +125,11 @@ var compactable = {
     shortestValue: '0',
     shorthand: true
   },
+  'font-size': {
+    canOverride: canOverride.unit,
+    defaultValue: 'medium',
+    shortestValue: '0'
+  },
   'height': {
     canOverride: canOverride.unit,
     defaultValue: 'auto',

test/fixtures/big-min.css

@@ -82,7 +82,7 @@ table{border-spacing:0;border-collapse:collapse}
 .ie .txt13_120,.ie .txt13_140{font-size:13px}
 .txt12{font-size:1.2rem}
 .txt11{font-size:1.1rem}
-.ie .txt11{font-size:11px}
+.btn_petit,.ie .txt11{font-size:11px}
 .txt10{font-size:1rem}
 .ie .txt10{font-size:10px}
 .container_18{margin:0 13px;width:974px}
@@ -182,7 +182,7 @@ table{border-spacing:0;border-collapse:collapse}
 * html .clearfix{height:1%}
 .clearfix{display:block}
 html{-webkit-text-size-adjust:100%;-ms-text-size-adjust:100%;font-size:62.5%}
-body{font-size:1.3rem;font-size:13px;line-height:140%;color:#16212c;background:#e9edf0}
+body{font-size:13px;line-height:140%;color:#16212c;background:#e9edf0}
 .global{width:1000px;margin:0 auto;padding:20px 0 10px;background:#fff}
 .lmd-header{position:relative;z-index:15}
 .lmd-footer #bandeau_bas{display:none}
@@ -210,7 +210,7 @@ section article{margin:0 0 16px}
 .txt_droite{text-align:right}
 .annotation{display:inline-block;font-size:10px;line-height:100%;color:#747b83}
 .nature_edito,.titre_blog{display:block}
-.nature_edito,.titre_blog,.type_element{font-size:11px;font-size:1.1rem;font-family:arial,sans-serif;font-weight:700;color:#a2a9ae;text-transform:uppercase}
+.nature_edito,.titre_blog,.type_element{font-size:1.1rem;font-family:arial,sans-serif;font-weight:700;color:#a2a9ae;text-transform:uppercase}
 .type_element{white-space:nowrap}
 .nature_edito{font-weight:400;font-size:16px;font-family:FetteEngschrift,'Arial Narrow',sans-serif}
 .bloc_bg_gris2{background:#f8f9fb;padding:8px 16px}
@@ -259,7 +259,7 @@ img[width="202"]{margin-bottom:4px}
 .bt_fonce a,.btn_fonce{color:#fff;background-color:#000b15;background-image:-moz-linear-gradient(top,#5d666d,#000b15);background-image:-ms-linear-gradient(top,#5d666d,#000b15);background-image:-webkit-gradient(linear,0 0,0 100%,from(#5d666d),to(#000b15));background-image:-webkit-linear-gradient(top,#5d666d,#000b15);background-image:-o-linear-gradient(top,#5d666d,#000b15);background-image:linear-gradient(top,#5d666d,#000b15);background-repeat:repeat-x;border-color:#000b15;border-color:rgba(0,0,0,.1)}
 .btn_abo{color:#000b15;background-color:#ffc600;background-image:-moz-linear-gradient(top,#ffe562,#ffc600);background-image:-ms-linear-gradient(top,#ffe562,#ffc600);background-image:-webkit-gradient(linear,0 0,0 100%,from(#ffe562),to(#ffc600));background-image:-webkit-linear-gradient(top,#ffe562,#ffc600);background-image:-o-linear-gradient(top,#ffe562,#ffc600);background-image:linear-gradient(top,#ffe562,#ffc600);background-repeat:repeat-x;border-color:#ffc600;border-color:rgba(0,0,0,.1)}
 .btn.large{width:100%;box-sizing:border-box;-moz-box-sizing:border-box;-webkit-box-sizing:border-box}
-.btn_petit{padding:2px 4px;font-size:11px;line-height:16px}
+.btn_petit{padding:2px 4px;line-height:16px}
 .btn:hover,.btn_abo:hover,.btn_fonce:hover,.btn_petit:hover{text-decoration:none;background-position:0 -15px;-webkit-transition:background-position .1s linear;-moz-transition:background-position .1s linear;-ms-transition:background-position .1s linear;-o-transition:background-position .1s linear;transition:background-position .1s linear}
 .btn:hover,.btn_petit:hover{color:#2e3942;background-color:#e6e6e6}
 .btn.active,.btn.disabled,.btn.disabled:hover,.btn:active,.btn[disabled],.btn_petit.active,.btn_petit:active,.btn_petit[disabled],input[type=submit].disabled{background-color:#e6e6e6;color:#d2d6db}
@@ -449,7 +449,7 @@ article .liste_carre_999{margin-top:5px}
 .global.debats .tt17_capital{margin:0 0 16px;padding:4px 0;border-bottom:1px solid #e9edf0;color:#000}
 .deroule_edito .liens_bas,.lien_chaine{width:100%;clear:both;padding:6px 0 0;margin:-3px 0 0;border-top:1px solid #eef1f5;text-align:center}
 .lien_chaine.lien_chaine_sans_bordure{border-top:0!important}
-.lien_chaine a,.lien_chaine span{color:#8b9299;font-weight:700;font-size:14px;font-size:1.4rem}
+.lien_chaine a,.lien_chaine span{color:#8b9299;font-weight:700;font-size:1.4rem}
 .deroule_edito .liens_bas{padding:6px 0;color:#d2d6db}
 .global.audience .container{overflow:hidden;height:176px}
 .global.audience .container>div{float:left;margin-left:16px}

test/optimizer/advanced-test.js

@@ -88,6 +88,10 @@ vows.describe('advanced optimizer')
   )
   .addBatch(
     optimizerContext('unit compacting', {
+      'font-size': [
+        'div{font-size:1rem;font-size:16px}',
+        'div{font-size:16px}'
+      ],
       'height': [
         'div{height:1rem;height:16px}',
         'div{height:16px}'