fix(Tab): remove invalid character in variable name

Author: guanpu

src/tab/scss/variable.scss

@@ -187,7 +187,7 @@ $tab-wrapped-border-line-style: $line-solid !default;
 /// @namespace size/tab
 $tab-wrapped-border-line-width: $line-1 !default;
 
-/// border width (non-active)
+/// border width (normal)
 /// @namespace size/tab
 $tab-wrapped-border-side-width: $line-1 !default;