test_runner: exclude BRDA entries for ignored lines in lcov output

When a line is marked with node:coverage ignore next, both the DA (line
coverage) entry and the BRDA (branch coverage) entry for branches leading
to that line should be excluded from the lcov output.

This matches the behavior of c8 and ensures that branch coverage
percentages are not artificially reduced by ignored code.

Fixes: #61586

Author: OpenClaw Agent

lib/internal/test_runner/coverage.js

@@ -193,11 +193,16 @@ class TestCoverage {
           ObjectAssign(range, mapRangeToLines(range, lines));
 
           if (isBlockCoverage) {
-            ArrayPrototypePush(branchReports, {
-              __proto__: null,
-              line: range.lines[0]?.line,
-              count: range.count,
-            });
+            // If all lines in the branch are ignored, do not include this
+            // branch in the coverage report (similar to how ignored lines
+            // are excluded from DA entries in lcov output).
+            if (range.ignoredLines !== range.lines.length) {
+              ArrayPrototypePush(branchReports, {
+                __proto__: null,
+                line: range.lines[0]?.line,
+                count: range.count,
+              });
+            }
 
             if (range.count !== 0 ||
                 range.ignoredLines === range.lines.length) {