associateSource method
Assign a SourceRange to this BlobNode's source
property.
Typically, this is used exclusively by the parser (notably, parseLibraryFile).
Tracking source location information introduces a memory overhead and should therefore only be used when necessary (e.g. for creating IDEs).
Calling this method replaces any existing association.
Implementation
void associateSource(SourceRange source) {
_sources[this] = source;
}