Intermittent tests.midlets.background.BackgroundMIDlet1 failure on Travis

[marco-c]

The first tests.midlets.background.BackgroundMIDlet1 test passes, the second fails with:

pre-main prep time: 0 ms
1.2:1.5  | DisplayDevice.isDisplayPrimary0.(I)Z not implemented (1) 
1.2:1.5  | MIDletSuiteImpl.lockMIDletSuite.(IZ)V not implemented (1, 0) 
1.2:1.5  | com/sun/midp/midletsuite/InstallInfo.load.()V incomplete 
1.2:1.5  | com/sun/j2me/content/InvocationStore.setCleanup0.(ILjava/lang/String;Z)V not implemented 
1.2:1.5  | Display.drawTrustedIcon0.(IZ)V not implemented (33554433, 1) 
1.2:1.5  | DisplayDevice.displayStateChanged0.(II)V not implemented (1, 0) 
1.2:1.5  | Hello World from background MIDlet 
2.3:5.5  | DisplayDevice.isDisplayPrimary0.(I)Z not implemented (1) 
2.3:5.5  | MIDletSuiteImpl.lockMIDletSuite.(IZ)V not implemented (1, 0) 
2.3:5.5  | com/sun/midp/midletsuite/InstallInfo.load.()V incomplete 
2.3:5.5  | Display.drawTrustedIcon0.(IZ)V not implemented (117440513, 1) 
2.3:5.5  | DisplayDevice.displayStateChanged0.(II)V not implemented (1, 0) 
1.2:2.10 | com/sun/j2me/content/AppProxy.midletIsAdded.(ILjava/lang/String;)V not implemented 
1.2:2.10 | com/sun/j2me/content/AppProxy.midletIsAdded.(ILjava/lang/String;)V not implemented 
2.3:5.5  | START - Background alarm started: 0 
         | [casper:debug] Set "null" field value to  
2.3:5.5  | com/sun/cdc/io/j2me/file/DefaultFileHandler.initialize.()V not implemented 
2.3:5.5  | UNKNOWN PROPERTY (com/sun/midp/main/Configuration): com.sun.io.j2me.fileHandlerImpl 
2.3:5.5  | DONE - Background alarm started: 1 
PASS Text doesn't exist within the document body
FAIL Find text within the document body
#    type: assertTextExists
#    file: /home/travis/build/mozilla/pluotsorbet/tests/automation.js
#    subject: false
#    text: "START - Background alarm started: 1"

[mykmelez]

I saw this on https://github.com/mozilla/pluotsorbet/pull/1807, but it went away in a rebuild. Bizarre.