fix(coverage): merge coverage ranges (#13334)

Covered ranges were not merged and thus it appeared that some lines
might be uncovered. To fix this I used "v8-coverage" that takes care
of merging the ranges properly. With this change, coverage collected
from a file by multiple entrypoints is now correctly calculated.

I ended up forking https://github.com/demurgos/v8-coverage and adding
"cli/tools/coverage/merge.rs" and "cli/tools/coverage/range_tree.rs".

1 files changed, 8 insertions, 0 deletions

diff --git a/cli/tests/testdata/coverage/multifile/a_test.js b/cli/tests/testdata/coverage/multifile/a_test.js
new file mode 100644
index 000000000..d5d9c3533
--- /dev/null
+++ b/cli/tests/testdata/coverage/multifile/a_test.js
@@ -0,0 +1,8 @@
+import { test } from "./mod.js";
+
+Deno.test({
+  name: "bugrepo a",
+  fn: () => {
+    test(true);
+  },
+});