> I'm also not sure the core dump was because of "out of memory".

out of memory: 0x0000000000020000 bytes requested
Segmentation fault (core dumped)
[..]
#0 0x0000097c6124c82a in kill () at <stdin>:2
#1 0x0000097c74ed6fd4 in XRE_FreeAppData ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#2 <signal handler called>
#3 0x0000097cd08b6957 in mozalloc_abort ()
from /usr/local/lib/firefox-esr-31.0/libmozalloc.so.1.0
#4 0x0000097cd08b6a07 in mozalloc_handle_oom ()
from /usr/local/lib/firefox-esr-31.0/libmozalloc.so.1.0
#5 0x0000097cd08b6707 in moz_xmalloc ()
from /usr/local/lib/firefox-esr-31.0/libmozalloc.so.1.0
#6 0x0000097c73667172 in NS_CycleCollectorSuspect3 ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#7 0x0000097c736624d0 in NS_DebugBreak ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#8 0x0000097c73660702 in NS_DebugBreak ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#9 0x0000097c75548bf9 in js::IterateGrayObjects ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#10 0x0000097c7554f8a5 in js::IterateGrayObjects ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#11 0x0000097c7555242c in js::IterateGrayObjects ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#12 0x0000097c7365e71f in NS_DebugBreak ()
---Type <return> to continue, or q <return> to quit---
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#13 0x0000097c7365e644 in NS_DebugBreak ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#14 0x0000097c73661e9c in NS_DebugBreak ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#15 0x0000097c736634ed in NS_DebugBreak ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#16 0x0000097c73664d0d in NS_DebugBreak ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#17 0x0000097c73665d7f in NS_CycleCollectorSuspect3 ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#18 0x0000097c74474d6a in DumpCompleteHeap ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#19 0x0000097c74475cdc in DumpCompleteHeap ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#20 0x0000097c736b2fcb in XRE_AddJarManifestLocation ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#21 0x0000097c736b3135 in XRE_AddJarManifestLocation ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#22 0x0000097c736b006d in XRE_AddJarManifestLocation ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#23 0x0000097c73648291 in ?? ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
---Type <return> to continue, or q <return> to quit---
#24 0x0000097c738b8006 in std::vector<std::pair<int, int>, std::allocator<std::pair<int, int> > >::_M_insert_aux ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#25 0x0000097c73888ec9 in std::_Rb_tree<int, std::pair<int const, std::string>, std::_Select1st<std::pair<int const, std::string> >, std::less<int>, std::allocator<std::pair<int const, std::string> > >::_M_erase ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#26 0x0000097c7431f7fe in js::BaseProxyHandler::finalizeInBackground ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#27 0x0000097c74f0bf93 in XRE_StartupTimelineRecord ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#28 0x0000097c74ecd2ea in XRE_InitCommandLine ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#29 0x0000097c74ecd4d1 in XRE_InitCommandLine ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#30 0x0000097c74ecd8b6 in XRE_main ()
from /usr/local/lib/firefox-esr-31.0/libxul.so.1.0
#31 0x0000097a4a703f87 in atexit () from /usr/local/bin/firefox-esr
#32 0x0000097a4a7038b1 in _start () from /usr/local/bin/firefox-esr
#33 0x0000000000000000 in ?? ()