Fix analyzer's handling of import prefixes not followed by '.'.

pkg/analyzer/test/generated/non_error_resolver_test.dart

Index: pkg/analyzer/test/generated/non_error_resolver_test.dart
diff --git a/pkg/analyzer/test/generated/non_error_resolver_test.dart b/pkg/analyzer/test/generated/non_error_resolver_test.dart
index 9974fc69836bc2737c9ea49a9c117d9c2bd151d8..7899ab738b2c6f92c7a4c4db6a6c462d5f486018 100644
--- a/pkg/analyzer/test/generated/non_error_resolver_test.dart
+++ b/pkg/analyzer/test/generated/non_error_resolver_test.dart
@@ -271,6 +271,28 @@ main() {
     verify([source]);
   }
 
+  void test_assignment_to_field_with_same_name_as_prefix() {
+    // If p is an import prefix, then within a method body, p = expr should be
+    // considered equivalent to this.p = expr.
+    addNamedSource("/lib.dart", r'''
+library lib;
+''');
+    Source source = addSource(r'''
+import 'lib.dart' as p;
+class Base {
+  var p;
+}
+class Derived extends Base {
+  f() {
+    p = 0;
+  }
+}
+''');
+    resolve(source);
+    assertErrors(source, [HintCode.UNUSED_IMPORT]);
+    verify([source]);
+  }
+
   void test_assignmentToFinal_prefixNegate() {
     Source source = addSource(r'''
 f() {
@@ -5157,6 +5179,28 @@ class B extends A {
     verify([source]);
   }
 
+  void test_unqualified_invocation_of_method_with_same_name_as_prefix() {
+    // If p is an import prefix, then within a method body, p() should be
+    // considered equivalent to this.p().
+    addNamedSource("/lib.dart", r'''
+library lib;
+''');
+    Source source = addSource(r'''
+import 'lib.dart' as p;
+class Base {
+  p() {}
+}
+class Derived extends Base {
+  f() {
+    p();
+  }
+}
+''');
+    resolve(source);
+    assertErrors(source, [HintCode.UNUSED_IMPORT]);
+    verify([source]);
+  }
+
   void test_unqualifiedReferenceToNonLocalStaticMember_fromComment_new() {
     Source source = addSource(r'''
 class A {