Skip /third_party/test262/ when computing browser-specific failures

/third_party/test262/ introduces Temporal tests as individual tests
instead of using the subtest WPT convention. These test failtures
misrepresent the overal interoperability of the web by causing the
single browser failure graph to be completely dominated by a feature
not yet shipped by all browsers.

Author: yulunwu2

browser-specific-failures.js

@@ -23,6 +23,37 @@ flags.defineBoolean('experimental', false,
     'Calculate metrics for experimental runs.');
 flags.parse();
 
+// WPT result paths to exclude from browser-specific-failure scoring.
+// /third_party/test262/ introduces Temporal tests as individual tests
+// instead of using the subtest WPT convention. These test failtures
+// misrepresent the overal interoperability of the web by causing the
+// single browser failure graph to be completely dominated by a feature
+// not yet shipped by all browsers.
+const EXCLUDED_PATHS = ['/third_party/test262'];
+
+// Returns a copy of |tree| with any subtrees whose path appears in
+// |excludedPaths| removed. Subtrees not on a path to an excluded entry are
+// shared by reference (no deep copy), so the operation is cheap.
+function pruneExcludedPaths(tree, excludedPaths, currentPath = '') {
+  const relevant = excludedPaths.filter(p =>
+      p.startsWith(currentPath + '/'));
+  if (relevant.length === 0) {
+    return tree;
+  }
+
+  const newTrees = {};
+  for (const [name, child] of Object.entries(tree.trees)) {
+    const childPath = `${currentPath}/${name}`;
+    if (relevant.includes(childPath)) {
+      continue;
+    }
+    newTrees[name] = relevant.some(p => p.startsWith(childPath + '/')) ?
+        pruneExcludedPaths(child, relevant, childPath) :
+        child;
+  }
+  return {...tree, trees: newTrees};
+}
+
 
 async function main() {
   // Sort the products so that output files are consistent.
@@ -78,6 +109,7 @@ async function main() {
         throw new Error('Run JSON contains "tree" field; code needs changed.');
       }
       run.tree = await lib.results.getGitTree(repo, run);
+      run.tree = pruneExcludedPaths(run.tree, EXCLUDED_PATHS);
     }
   }
   after = Date.now();