extractors/dart.py hardcoded source_location: None at every node and
edge construction site, so a Dart graph could cite zero lines no
matter how many declarations it had (0% across three real repos,
~25k unciteable nodes in one of them).
Threads a line number through add_node/add_edge from each match's own
offset, anchored on the capture group rather than the whole match: a
pattern like the class declaration's leading ^\s* otherwise reports
the line too early when blank lines precede the declaration.
The comment stripping pass also needed a fix first: it deleted a
comment token outright, so a multi-line comment shifted every later
offset (and therefore every later line number) up by the comment's
own height. Blanking it to the same number of newlines instead keeps
src_clean's line count in step with the original file.
Sourceless reference stub nodes (an inherited class, a mixin, an
import target, and similar names the file only references rather
than defines) keep source_location: None, same as before, since there
is no single line in THIS file for a symbol that lives elsewhere.
Every node this file actually defines, and every edge attributed to a
real declaration site, now carries its real line.
Fixes#3365.
(cherry picked from commit 0dbcefc5ba)
Modernizes the Dart extractor: comment stripping, `part of` redirection, nested-generic-aware extends/with/implements parsing, generic type-argument mapping, and generic call detection.
Verified against current v8: merges cleanly, full suite 1530 passed, and inheritance edges connect to same-file class nodes with no ghost-node splits or dangling edges (consistent with the #1033/#1096 node-ID invariants).