code: function validateExpression( node ) {
  		var args,
  			len,
  			re,
  			i;
  
  		if ( node.callee.name === 'RegExp' ) {
  			len = node.arguments.length;
  			args = new Array( node.arguments.length );
  			for ( i = 0; i < len; i++ ) {
  				// NOTE: we only support literals ATM. Otherwise, we may need to walk and implement an entire tree.
  				if ( node.arguments[ i ].type !== 'Literal' ) {
  					return;
  				}
  				args[ i ] = node.arguments[ i ].value;
  			}
  			re = RegExp.apply( null, args );
  			if ( !safe( re ) ) {
  				context.report( node, 'Unsafe regular expression' );
  			}
  		}
  	}
docs: end FUNCTION validateLiteral() 
  FUNCTION: validateExpression( node )
  Validates a regular expression creating using the `RegExp` constructor.
  
  @param {Node} node - AST node
  @returns {Void}