Issue 26426. Don't use SDK summarie when analyzing SDK itself.

pkg/analyzer_cli/lib/src/driver.dart

Index: pkg/analyzer_cli/lib/src/driver.dart
diff --git a/pkg/analyzer_cli/lib/src/driver.dart b/pkg/analyzer_cli/lib/src/driver.dart
index 4942015e2c192b1339f78f610338d0d1cbfd69f7..6effac46e8c23428412b34e87664bc549de731c1 100644
--- a/pkg/analyzer_cli/lib/src/driver.dart
+++ b/pkg/analyzer_cli/lib/src/driver.dart
@@ -587,8 +587,13 @@ class Driver implements CommandLineStarter {
     // the command lines sent to stdin.  So process it before deciding whether
     // to activate batch mode.
     if (sdk == null) {
-      sdk = new DirectoryBasedDartSdk(new JavaFile(options.dartSdkPath));
-      sdk.useSummary = true;
+      String dartSdkPath = options.dartSdkPath;
+      sdk = new DirectoryBasedDartSdk(new JavaFile(dartSdkPath));
+      sdk.useSummary = options.sourceFiles.every((String sourcePath) {
+            sourcePath = path.absolute(sourcePath);
+            sourcePath = path.normalize(sourcePath);
+            return !path.isWithin(dartSdkPath, sourcePath);
+          });
       sdk.analysisOptions = createAnalysisOptionsForCommandLineOptions(options);
     }
     _isBatch = options.shouldBatch;