Add the ability to ignore lines depending on comments (#58656)

https://github.com/dart-lang/coverage - 0.14.0 added the ability to be able to ignore coverage depending on comments.

// coverage:ignore-line to ignore one line.
// coverage:ignore-start and // coverage:ignore-end to ignore range of lines inclusive.
// coverage:ignore-file to ignore the whole file.

packages/flutter_tools/lib/src/test/coverage_collector.dart

@@ -66,7 +66,11 @@ class CoverageCollector extends TestWatcher {
     assert(data != null);
 
     _logMessage('($observatoryUri): collected coverage data; merging...');
-    _addHitmap(await coverage.createHitmap(data['coverage'] as List<Map<String, dynamic>>));
+    _addHitmap(await coverage.createHitmap(
+      data['coverage'] as List<Map<String, dynamic>>,
+      packagesPath: globalPackagesPath,
+      checkIgnoredLines: true,
+    ));
     _logMessage('($observatoryUri): done merging coverage data into global coverage map.');
   }
 
@@ -98,7 +102,11 @@ class CoverageCollector extends TestWatcher {
     assert(data != null);
 
     _logMessage('pid $pid ($observatoryUri): collected coverage data; merging...');
-    _addHitmap(await coverage.createHitmap(data['coverage'] as List<Map<String, dynamic>>));
+    _addHitmap(await coverage.createHitmap(
+      data['coverage'] as List<Map<String, dynamic>>,
+      packagesPath: globalPackagesPath,
+      checkIgnoredLines: true,
+    ));
     _logMessage('pid $pid ($observatoryUri): done merging coverage data into global coverage map.');
   }