Improve descriptions of JS for snippets

More specifically than "faster" and not faster, these snippets count
down and count up, respectively. Adding this information to the
descriptions will help people make the correct decision.

UltiSnips/javascript.snippets

@@ -32,13 +32,13 @@ ${1:class_name}.prototype.${2:method_name} = function(${3:first_argument}) {
 
 endsnippet
 
-snippet for "for (...) {...} (faster)"
+snippet for "for (...) {...} (counting down, faster)"
 for (var ${2:i} = ${1:Things.length} - 1; $2 >= 0; $2--) {
 	${3:${1/([^.]+).*/$1/}[$2]}${VISUAL}$0
 }
 endsnippet
 
-snippet for "for (...) {...}"
+snippet for "for (...) {...} (counting up)"
 for (var ${1:i} = 0, ${2:len} = ${3:Things.length}; $1 < $2; $1++) {
 	${4:${3/([^.]+).*/$1/}[$1]}${VISUAL}$0
 }