addSpan method
Adds an entry mapping target to source.
If isIdentifier is true or if target is a SourceMapSpan with
isIdentifier set to true, this entry is considered to represent an
identifier whose value will be stored in the source map. isIdentifier
takes precedence over target's isIdentifier value.
Implementation
void addSpan(SourceSpan source, SourceSpan target, {bool? isIdentifier}) {
isIdentifier ??= source is SourceMapSpan ? source.isIdentifier : false;
var name = isIdentifier ? source.text : null;
_entries.add(Entry(source.start, target.start, name));
}