Safari 7.0.6 crashes: Dyld Error Message: Symbol Not Found

Question

After I did the latest MacOS update (10.9.5) Safari (7.0.6) no longer runs. I repaired permissions and also rebooted in safe mode so I could potentially remove any spurious plug-ins, but the last time I did this was with MaxOS 6 so I have no idea where to look in the current version.
The error message that pops up is:
Process:         Safari [1279]
Path:            /Applications/Safari.app/Contents/MacOS/Safari
Identifier:      com.apple.Safari
Version:         ???
Build Info:      WebBrowser-7537085010017001~4
Code Type:       X86-64 (Native)
Parent Process:  launchd [194]
Responsible:     Safari [1279]
User ID:         505
Date/Time:       2014-09-26 08:16:17.066 +1000
OS Version:      Mac OS X 10.9.5 (13F34)
Report Version:  11
Anonymous UUID:  84ADDFB5-CAD4-0759-3667-8E0B47E8E995
Sleep/Wake UUID: 51EC656E-25AB-4167-810D-D7A644340E28
Crashed Thread:  0
Exception Type:  EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000002, 0x0000000000000000
Application Specific Information:
dyld: launch, loading dependent libraries, ignoring DYLD_* env vars
Dyld Error Message:
Symbol not found: __ZN3JSC10JSDataView6s_infoE
Referenced from: /System/Library/StagedFrameworks/Safari/WebCore.framework/Versions/A/WebCore
Expected in: /System/Library/Frameworks/JavaScriptCore.framework/Versions/A/JavaScriptCore
in /System/Library/StagedFrameworks/Safari/WebCore.framework/Versions/A/WebCore
(insert a 'shed load' of other lines of log data which you probably don't need, right?)

Answer 1

If you don't already have a current backup, back up all data, then reinstall the OS.* You don't need to erase the startup volume, and you won't need the backup unless something goes wrong. If the system was upgraded from an older version of OS X, you may need the Apple ID and password you used.
If you use FileVault 2, then before running the Installer you must launch Disk Utility and select the icon of the FileVault startup volume ("Macintosh HD," unless you gave it a different name.) It will be nested below another icon with the same name. Click the Unlock button in the toolbar and enter your login password when prompted. Then quit Disk Utility to be returned to the main Recovery screen.
There are ways to back up a computer that isn't fully functional. Ask if you need guidance.
If you installed the Java runtime distributed by Apple and still need it, you'll have to reinstall it. The same goes for Xcode. All other data will be preserved.
*The linked support article refers to OS X 10.9 ("Mavericks"), but the procedure is the same for OS X 10.7 ("Lion") and later.