Analyzer: avoid dynamic calls while examining Yaml

Change-Id: If569c74bad1d3762deb4cc74ea617d291ec33619
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/190727
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/lib/src/pubspec/pubspec_validator.dart

@@ -157,7 +157,7 @@ class PubspecValidator {
     }
 
     for (var dependency in declaredDevDependencies.entries) {
-      var packageName = dependency.key;
+      var packageName = dependency.key as YamlNode;
       if (declaredDependencies.containsKey(packageName)) {
         _reportErrorForNode(reporter, packageName,
             PubspecWarningCode.UNNECESSARY_DEV_DEPENDENCY, [packageName.value]);

pkg/analyzer/lib/src/util/yaml.dart

@@ -118,8 +118,12 @@ class Merger {
       merged[k] = v;
     });
     m2.nodes.forEach((k, v) {
+      // TODO(srawlins): The key should always be a [YamlNode], but is not (see
+      // https://pub.dev/documentation/yaml/latest/yaml/YamlMap/nodes.html).
+      // We could write an extension method which does this cast for us.
+      var value = (k as YamlNode).value;
       var mergedKey =
-          merged.keys.firstWhere((key) => key.value == k.value, orElse: () => k)
+          merged.keys.firstWhere((key) => key.value == value, orElse: () => k)
               as YamlScalar;
       var o1 = merged[mergedKey];
       if (o1 != null) {

pkg/analyzer/lib/src/workspace/package_build.dart

@@ -287,7 +287,7 @@ class PackageBuildWorkspace extends Workspace {
       // pubspec, to know the package name that package:build will assume.
       if (dartToolBuildDir.exists && pubspec.exists) {
         try {
-          final yaml = loadYaml(pubspec.readAsStringSync());
+          final yaml = loadYaml(pubspec.readAsStringSync()) as YamlMap;
           final packageName = yaml['name'] as String;
           final generatedRootPath = provider.pathContext
               .joinAll([folder.path, ..._generatedPathParts]);

pkg/analyzer/tool/experiments/generate.dart

@@ -68,7 +68,7 @@ part of 'experiments.dart';
     features = <String, dynamic>{};
     Map yamlFeatures = experimentsYaml['features'];
     for (MapEntry entry in yamlFeatures.entries) {
-      String category = entry.value['category'] ?? 'language';
+      String category = (entry.value as YamlMap)['category'] ?? 'language';
       if (category != "language") {
         // Skip a feature with a category that's not language. In the future
         // possibly allow e.g. 'analyzer' etc.