erroneous dot file generated from Nashorn --print-code

If an exception is raised during dot file generation, a catch message is inserted in the label of a graph node, followed by a line break. The dot processor interprets this as a string running past the EOL.

Example (the input is the JavaScript function "var f = function(a) { return a+4 }") - there is a hard line break after the three closing asterisks:

    L2 [id=L2, label="*** CATCH: jdk/nashorn/internal/runtime/UnwarrantedOptimismException ***
    L2 [bci=8]\lframe same1 UnwarrantedOptimismException\l\l 8 iconst_2\l 9 anewarray Object\l 12 aload 0\l 13 iload 1\l 14 invokedynamic populateArray([Object;Object;I)[Object; [static 'populateArrayBootstrap']\l 19 iconst_0\l 20 invokestatic Script$Recompilation$4$8I$\^shell\_.:getString$array(I)[String;\l 23 invokestatic RewriteException.create(UnwarrantedOptimismException;[Object;[String;)RewriteException;\l 26 athrow\l"]

Proposed solution: to make the text contained in the graph consistent with what the --print-code option outputs to the console, omit the catch message altogether.

Attached noreg-other label as this is debugging infrastructure.