Removed the unnecessary declarations

margin-top:auto; and margin-bottom:auto are the same as margin-top:0; and margin-bottom:0;

core/spacing/space.css

@@ -48,7 +48,5 @@ s,m,l,n = small(5px),medium(10px),large(20px),none(0px)
 .mls,.mhs,.mas{margin-left:5px !important}
 .mlm,.mhm,.mam{margin-left:10px !important}
 .mll,.mhl,.mal{margin-left:20px !important}
-.mta,.mva,.maa{margin-top:auto !important}
-.mra,.mha,.maa{margin-right:auto !important}
-.mba,.mva,.maa{margin-bottom:auto !important}  
-.mla,.mha,.maa{margin-left:auto !important}
+.mra,.mha{margin-right:auto !important}
+.mla,.mha{margin-left:auto !important}