Disable false positive ShellCheck warnings SC2154

ShellCheck thinks these variables are unused. However, one of the
exceptions applies here:

> ShellCheck does not attempt to figure out runtime or dynamic
> assignments like with source mycommonvars.sh or eval var=value.

${useragent[$uakey]} in line 337 references these variables.

google-font-download

@@ -241,9 +241,14 @@ fi
 
 # Store the useragents we're going to use to trick Google's servers into serving us the correct CSS file.
 declare -A useragent
+# ShellCheck doesn't correctly notice our dynamic use of these variables.
+# shellcheck disable=SC2154
 useragent[eot]='Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0)'
+# shellcheck disable=SC2154
 useragent[woff]='Mozilla/5.0 (Windows NT 6.1; WOW64; rv:27.0) Gecko/20100101 Firefox/27.0'
+# shellcheck disable=SC2154
 useragent[svg]='Mozilla/4.0 (iPad; CPU OS 4_0_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/4.1 Mobile/9A405 Safari/7534.48.3'
+# shellcheck disable=SC2154
 useragent[ttf]='Mozilla/5.0 (Windows NT 6.1) AppleWebKit/534.54.16 (KHTML, like Gecko) Version/5.1.4 Safari/534.54.16'
 
 # Clear the output file