Web Inspector: File system should produce more verbose error messages and recover from errors
https://bugs.webkit.org/show_bug.cgi?id=109571

Reviewed by Alexander Pavlov.

Error handler prints original file system call params now.
Added callbacks to error handler to recover from errors.

* inspector/front-end/FileSystemProjectDelegate.js:
(WebInspector.FileSystemProjectDelegate.prototype.contentCallback):
(WebInspector.FileSystemProjectDelegate.prototype.searchInFileContent):
(WebInspector.FileSystemUtils.errorMessage):
(.fileSystemLoaded):
(.fileEntryLoaded):
(.errorHandler):
(WebInspector.FileSystemUtils.requestFileContent):
(WebInspector.FileSystemUtils.setFileContent):
(WebInspector.FileSystemUtils._readDirectory):
(.innerCallback):
(WebInspector.FileSystemUtils._requestEntries):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@142613 268f45cc-cd09-0410-ab3c-d52691b4dbfc