This implements a reduced variant of #1226 with just the following
change:
-Fatal error: Uncaught exception 'EngineException' with message 'Call to private method foo::bar() from context ''' in %s:%d
+Fatal error: Uncaught EngineException: Call to private method foo::bar() from context '' in %s:%d
The '' wrapper around messages is very weird if the exception
message itself contains ''. Futhermore having the message wrapped
in '' doesn't work for the "and defined" suffix of
TypeExceptions.
TypeException stays as-is for now because it uses messages that are
incompatible with the way exception messages are displayed.
closure_038.phpt and a few others now show that we're generating
too many exceptions for compound operations on undefined properties
-- this needs to be fixed in a followup.
