Fix http://dev.processing.org/bugs/show_bug.cgi?id=1188 .

Of course, in order to enable assertions, you have to run the JVM with the -ea switch. Should we detect the use of assertions (easily done) and set a flag (as we do with "hasMain", etc.)?

app/src/processing/app/preproc/PdeEmitter.java

@@ -546,6 +546,7 @@ public class PdeEmitter implements PdeTokenTypes {
       break;
 
     case LITERAL_synchronized: // 0137 to fix bug #136
+    case LITERAL_assert:
       out.print(ast.getText());
       dumpHiddenAfter(ast);
       printChildren(ast);