StackTrace.fromString constructor
Create a StackTrace object from stackTraceString.
The created stack trace will have a toString method returning
stackTraceString.
The stackTraceString can be a string returned by some other
stack trace, or it can be any string at all.
If the string doesn't look like a stack trace, code that interprets
stack traces is likely to fail, so fake stack traces should be used
with care.
Implementation
factory StackTrace.fromString(String stackTraceString) = _StringStackTrace;