In summary linker, drop trailing type args of type `dynamic`.

pkg/analyzer/test/src/summary/summary_common.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.test.src.summary.summary_common;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/dart/scanner/reader.dart';
@@ skipping 7280 matching lines @@
 
   test_import_uri() {
     String uriString = '"dart:async"';
     String libraryText = 'import $uriString; Future x;';
     serializeLibraryText(libraryText);
     // Second import is the implicit import of dart:core
     expect(unlinkedUnits[0].imports, hasLength(2));
     expect(unlinkedUnits[0].imports[0].uri, 'dart:async');
   }
 
+  test_inferred_type_keeps_leading_dynamic() {
+    if (!strongMode || skipFullyLinkedData) {
+      return;
+    }
+    UnlinkedClass cls =
+        serializeClassText('class C { final x = <dynamic, int>{}; }');
+    EntityRef type = getTypeRefForSlot(cls.fields[0].inferredTypeSlot);
+    // Check that x has inferred type `Map<dynamic, int>`.
+    checkLinkedTypeRef(type, 'dart:core', 'dart:core', 'Map',
+        allowTypeArguments: true, numTypeParameters: 2);
+    expect(type.typeArguments, hasLength(2));
+    checkLinkedTypeRef(type.typeArguments[0], null, null, 'dynamic');
+    checkLinkedTypeRef(type.typeArguments[1], 'dart:core', 'dart:core', 'int');
+  }
+
   test_inferred_type_refers_to_bound_type_param() {
     if (!strongMode || skipFullyLinkedData) {
       return;
     }
     UnlinkedClass cls = serializeClassText(
         'class C<T> extends D<int, T> { var v; }'
         ' abstract class D<U, V> { Map<V, U> get v; }',
         className: 'C');
     EntityRef type = getTypeRefForSlot(cls.fields[0].inferredTypeSlot);
     // Check that v has inferred type Map<T, int>.
@@ skipping 117 matching lines @@
     expect(linkedReference.dependency, 0);
     expect(linkedReference.kind, ReferenceKind.propertyAccessor);
     expect(linkedReference.name, 'f=');
     expect(linkedReference.numTypeParameters, 0);
     expect(linkedReference.unit, 0);
     expect(linkedReference.containingReference, isNot(0));
     expect(linkedReference.containingReference, lessThan(type.reference));
     checkReferenceIndex(linkedReference.containingReference, null, null, 'D');
   }
 
+  test_inferred_type_skips_trailing_dynamic() {
+    if (!strongMode || skipFullyLinkedData) {
+      return;
+    }
+    UnlinkedClass cls =
+        serializeClassText('class C { final x = <int, dynamic>{}; }');
+    EntityRef type = getTypeRefForSlot(cls.fields[0].inferredTypeSlot);
+    // Check that x has inferred type `Map<int>`.  The trailing type argument
+    // `dynamic` is omitted.
+    checkLinkedTypeRef(type, 'dart:core', 'dart:core', 'Map',
+        allowTypeArguments: true, numTypeParameters: 2);
+    expect(type.typeArguments, hasLength(1));
+    checkLinkedTypeRef(type.typeArguments[0], 'dart:core', 'dart:core', 'int');
+  }
+
+  test_inferred_type_skips_unnecessary_dynamic() {
+    if (!strongMode || skipFullyLinkedData) {
+      return;
+    }
+    UnlinkedClass cls = serializeClassText('class C { final x = []; }');
+    EntityRef type = getTypeRefForSlot(cls.fields[0].inferredTypeSlot);
+    // Check that x has inferred type `List`, not `List<dynamic>`.
+    checkLinkedTypeRef(type, 'dart:core', 'dart:core', 'List',
+        numTypeParameters: 1);
+  }
+
   test_initializer_executable_with_bottom_return_type() {
     // The synthetic executable for `v` has type `() => Bottom`.
     UnlinkedVariable variable = serializeVariableText('int v = null;');
     expect(variable.initializer.returnType, isNull);
     checkInferredTypeSlot(
         variable.initializer.inferredReturnTypeSlot, null, null, '*bottom*',
         onlyInStrongMode: false);
   }
 
   test_initializer_executable_with_imported_return_type() {
@@ skipping 1868 matching lines @@
 class _PrefixExpectation {
   final ReferenceKind kind;
   final String name;
   final String absoluteUri;
   final String relativeUri;
   final int numTypeParameters;
 
   _PrefixExpectation(this.kind, this.name,
       {this.absoluteUri, this.relativeUri, this.numTypeParameters: 0});
 }