Fix typo in TestMojo
Fix typo in TestMojo

TODO: only pass boolean flags that differ from their default value. Some
flags conflict with each others, and order matters. I made the same mistake
in CodeHaus' plugin: gwt-maven-plugin/gwt-maven-plugin@8fda6bba, partially
reverted in gwt-maven-plugin/gwt-maven-plugin@0f548387

tbroyer/gwt-maven-plugin,tbroyer/gwt-maven-plugin