Core: fix code style

[bytestream]

Description

Build is failing as a result of #2154

Running "jscs:all" (jscs) task
If statement without curly braces at src/core.js :
  1033 |  // as a literal part of a name/id or any selector.
  1034 |  escapeCssMeta: function( string ) {
  1035 |   if (string === undefined) return "";
-----------^
  1036 |   return string.replace( /([\\!"#$%&'()*+,./:;<=>?@\[\]^`{|}~])/g, "\\$1" );
  1037 |  },
Missing space after opening round bracket at src/core.js :
  1033 |  // as a literal part of a name/id or any selector.
  1034 |  escapeCssMeta: function( string ) {
  1035 |   if (string === undefined) return "";
---------------^
  1036 |   return string.replace( /([\\!"#$%&'()*+,./:;<=>?@\[\]^`{|}~])/g, "\\$1" );
  1037 |  },
Missing space before closing round bracket at src/core.js :
  1033 |  // as a literal part of a name/id or any selector.
  1034 |  escapeCssMeta: function( string ) {
  1035 |   if (string === undefined) return "";
-----------------------------------^
  1036 |   return string.replace( /([\\!"#$%&'()*+,./:;<=>?@\[\]^`{|}~])/g, "\\$1" );
  1037 |  },
>> 3 code style errors found!
Warning: Task "jscs:all" failed. Use --force to continue.

Aborted due to warnings.
npm ERR! code ELIFECYCLE
npm ERR! errno 3
npm ERR! jquery-validation@1.19.4-pre prepublish: `grunt`
npm ERR! Exit status 3
npm ERR! 
npm ERR! Failed at the jquery-validation@1.19.4-pre prepublish script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

Thank you!