Fix errors reported by the no-multiple-empty-lines ESLint rule

http://eslint.org/docs/rules/no-multiple-empty-lines

extensions/firefox/content/PdfjsChromeUtils.jsm

@@ -338,4 +338,3 @@ var PdfjsChromeUtils = {
     });
   }
 };
-

external/crlfchecker/crlfchecker.js

@@ -24,4 +24,3 @@ function checkIfCrlfIsPresent(files) {
 }
 
 exports.checkIfCrlfIsPresent = checkIfCrlfIsPresent;
-

test/unit/jasmine-boot.js

@@ -203,4 +203,3 @@ function initializePDFJS(callback) {
     return destination;
   }
 }());
-

test/unit/ui_utils_spec.js

@@ -117,4 +117,3 @@ describe('ui_utils', function() {
     });
   });
 });
-