remove unnecessary classes from startup

[mykmelez]

J2ME startup is fairly complex, with a variety of classes getting loaded and instantiated, and I wonder if it's all strictly necessary in our environment, which only runs a single midlet (or two, if there's a background midlet). Here's part of a stack trace that shows the complexity of the class hierarchy just to start a midlet:

javax/microedition/midlet/MIDletTunnelImpl.callStartApp(), bci=0 com/sun/midp/midlet/MIDletPeer.startApp(), bci=0 com/sun/midp/midlet/MIDletStateHandler.startSuite(), bci=0 com/sun/midp/main/AbstractMIDletSuiteLoader.startSuite(), bci=0 com/sun/midp/main/CldcMIDletSuiteLoader.startSuite(), bci=0 com/sun/midp/main/AbstractMIDletSuiteLoader.runMIDletSuite(), bci=0 com/sun/midp/main/MIDletSuiteLoader.main(), bci=0"

And there are other classes that these classes load, like InvocationStore, whose purpose is apparently to queue invocations of other midlets (which doesn't happen in our environment, as far as I know; we do handle MIDlet.platformRequest, but that doesn't seem to use it).

We should investigate how much of this machinery we can remove while still enabling a midlet to load and run.

[marco-c]

https://github.com/mozilla/j2me.js/pull/1303 is a first step.

[marco-c]

I've added a few performance.now() calls to understand where we're spending time:

CldcMIDletSuiteLoader before init(): 3399
CldcMIDletSuiteLoader after init(): 3755
CldcMIDletSuiteLoader after createSuiteEnvironment(): 4519
CldcMIDletSuiteLoader after createMIDletSuite(): 4682
CldcMIDletSuiteLoader before startSuite(): 5058
MIDletTunnelImpl.callStartApp: 5791
BGUtils.startMIDlet: 7475
AmsUtil before isolate.start(): 7535
AppIsolateMIDletSuiteLoader after init(): 8872
CldcMIDletSuiteLoader before init(): 8909
CldcMIDletSuiteLoader after init(): 9856
CldcMIDletSuiteLoader after createSuiteEnvironment(): 9943
CldcMIDletSuiteLoader after createMIDletSuite(): 9968
CldcMIDletSuiteLoader before startSuite(): 9979
MIDletTunnelImpl.callStartApp: 10382