Firefox is crashing and/or applets fail to get loaded when working with an application with very rich user interface and lots of applets which get loaded and unloaded.

This is a continuation of the issue JDK-7040632.

A thread dump of Firefox crash, which was provided by the person who reproduced it, is attached to this bug as "ThreadDumpOfFirefoxCrash.zip" file. Call stacks of 2 threads from the thread dump which are related to the crash are presented below.

---------- Call stacks of 2 threads ----------
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 libsystem_kernel.dylib 0x00007fff94ee7ce2 __pthread_kill + 10
1 libsystem_c.dylib 0x00007fff8fa9d7d2 pthread_kill + 95
2 libsystem_c.dylib 0x00007fff8fa8ea7a abort + 143
3 libc++abi.dylib 0x00007fff8c26c7bc abort_message + 214
4 libc++abi.dylib 0x00007fff8c269fcf default_terminate() + 28
5 libobjc.A.dylib 0x00007fff8d6c71cd _objc_terminate + 114
6 libc++abi.dylib 0x00007fff8c26a001 safe_handler_caller(void (*)()) + 11
7 libc++abi.dylib 0x00007fff8c26a05c std::terminate() + 16
8 libc++abi.dylib 0x00007fff8c26b152 __cxa_throw + 114
9 com.oracle.java.JavaAppletPlugin 0x000000011a709ec4 Jpi_PThread_ConditionVariable::~Jpi_PThread_ConditionVariable() + 70
10 com.oracle.java.JavaAppletPlugin 0x000000011a70a424 Jpi_PluginEscort::~Jpi_PluginEscort() + 34
11 com.oracle.java.JavaAppletPlugin 0x000000011a7064bc NPAPIJavaPlugin::nppDestroy() + 124
12 com.oracle.java.JavaAppletPlugin 0x000000011a703547 NPP_Destroy + 26
13 XUL 0x0000000101cd98cb 0x101000000 + 13473995
14 XUL 0x0000000101ce9b38 0x101000000 + 13540152
15 XUL 0x00000001014c5a4e 0x101000000 + 5003854
    ...
39 XUL 0x00000001020efafb 0x101000000 + 17758971
40 XUL 0x0000000101dd91b0 0x101000000 + 14520752
41 XUL 0x0000000101d928c9 0x101000000 + 14231753
42 com.apple.CoreFoundation 0x00007fff8cab44f1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
43 com.apple.CoreFoundation 0x00007fff8cab3d5d __CFRunLoopDoSources0 + 253
44 com.apple.CoreFoundation 0x00007fff8cadab49 __CFRunLoopRun + 905
45 com.apple.CoreFoundation 0x00007fff8cada486 CFRunLoopRunSpecific + 230
46 com.apple.HIToolbox 0x00007fff914722bf RunCurrentEventLoopInMode + 277
47 com.apple.HIToolbox 0x00007fff914794bf ReceiveNextEventCommon + 181
48 com.apple.HIToolbox 0x00007fff914793fa BlockUntilNextEventMatchingListInMode + 62
49 com.apple.AppKit 0x00007fff93765779 _DPSNextEvent + 659
50 com.apple.AppKit 0x00007fff9376507d -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 135
51 XUL 0x0000000101d91f42 0x101000000 + 14229314
52 com.apple.AppKit 0x00007fff937619b9 -[NSApplication run] + 470
53 XUL 0x0000000101d9306b 0x101000000 + 14233707
54 XUL 0x0000000101c20664 0x101000000 + 12715620
55 XUL 0x00000001010095fa 0x101000000 + 38394
56 XUL 0x000000010100986e 0x101000000 + 39022
57 XUL 0x0000000101009b94 XRE_main + 244
58 org.mozilla.firefox 0x000000010000167b 0x100000000 + 5755
59 org.mozilla.firefox 0x0000000100000d74 start + 52

Thread 43:
0 libsystem_kernel.dylib 0x00007fff94ee7bb6 __psynch_cvsignal + 10
1 libsystem_c.dylib 0x00007fff8fa9f65a pthread_cond_signal_thread_np + 692
2 com.oracle.java.JavaAppletPlugin 0x000000011a709f7c Jpi_PThread_ConditionVariable::notify() + 18
3 com.oracle.java.JavaAppletPlugin 0x000000011a70a771 Jpi_PluginEscort::push(void*) + 65
4 com.oracle.java.JavaAppletPlugin 0x000000011a70a6a3 PluginRunner::run(Jpi_Thread&) + 371
5 com.oracle.java.JavaAppletPlugin 0x000000011a709a44 pthread_fn + 10
6 libsystem_c.dylib 0x00007fff8fa9b8bf _pthread_start + 335
7 libsystem_c.dylib 0x00007fff8fa9eb75 thread_start + 13