do not suggest import uri reaching out of lib

pkg/analysis_server/lib/src/services/completion/dart/uri_contributor.dart

Index: pkg/analysis_server/lib/src/services/completion/dart/uri_contributor.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/uri_contributor.dart b/pkg/analysis_server/lib/src/services/completion/dart/uri_contributor.dart
index 13282c2fdb2eef21b13aeb648d1dd02fdafe0d06..7e849b148930d4f3aad760b920dfeb42e0ea6f71 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/uri_contributor.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/uri_contributor.dart
@@ -116,10 +116,16 @@ class _UriSuggestionBuilder extends SimpleAstVisitor {
     if (resContext.isRelative(dirPath)) {
       String sourceDirPath = resContext.dirname(source.fullName);
       if (resContext.isAbsolute(sourceDirPath)) {
-        dirPath = resContext.join(sourceDirPath, dirPath);
+        dirPath = resContext.normalize(resContext.join(sourceDirPath, dirPath));
       } else {
         return;
       }
+      // Do not suggest relative paths reaching outside the 'lib' directory.
+      bool srcInLib = resContext.split(sourceDirPath).contains('lib');
+      bool dstInLib = resContext.split(dirPath).contains('lib');
+      if (srcInLib && !dstInLib) {
+        return;
+      }
     }
     if (dirPath.endsWith('\\.')) {
       dirPath = dirPath.substring(0, dirPath.length - 1);