Simplify how patch files are specified to analyzer.

pkg/analyzer/test/generated/engine_test.dart

Index: pkg/analyzer/test/generated/engine_test.dart
diff --git a/pkg/analyzer/test/generated/engine_test.dart b/pkg/analyzer/test/generated/engine_test.dart
index 5822a2d62232cd58141ded34094b023bc3e6796d..954966d0535f2b92ff41300774ac751de4a7d6f3 100644
--- a/pkg/analyzer/test/generated/engine_test.dart
+++ b/pkg/analyzer/test/generated/engine_test.dart
@@ -58,7 +58,9 @@ class AnalysisOptionsImplTest {
     modifiedOptions.incrementalValidation = true;
     modifiedOptions.lint = true;
     modifiedOptions.lintRules = [null];
-    modifiedOptions.patchPlatform = 3;
+    modifiedOptions.patchPaths = {
+      'dart:core': ['/dart_core.patch.dart']
+    };
     modifiedOptions.preserveComments = false;
     modifiedOptions.strongMode = true;
     modifiedOptions.trackCacheDependencies = false;
@@ -91,7 +93,7 @@ class AnalysisOptionsImplTest {
         defaultOptions.incrementalValidation);
     expect(modifiedOptions.lint, defaultOptions.lint);
     expect(modifiedOptions.lintRules, defaultOptions.lintRules);
-    expect(modifiedOptions.patchPlatform, defaultOptions.patchPlatform);
+    expect(modifiedOptions.patchPaths, defaultOptions.patchPaths);
     expect(modifiedOptions.preserveComments, defaultOptions.preserveComments);
     expect(modifiedOptions.strongMode, defaultOptions.strongMode);
     expect(modifiedOptions.trackCacheDependencies,