Lift nearly all top-level type inference restrictions.

pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart

Index: pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
diff --git a/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart b/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
index f51ba659ba6d2a52f6cb2b01ac588e897e9452d4..8b56013254df04d8b1776370edcafc7e7e46c82d 100644
--- a/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
+++ b/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
@@ -231,6 +231,8 @@ abstract class TypeInferrerImpl extends TypeInferrer {
   /// Not used when performing local inference.
   bool isImmediatelyEvident = true;
 
+  List<FieldNode> _dryRunDependencies;
+
   TypeInferrerImpl(TypeInferenceEngineImpl engine, this.uri, this.listener,
       bool topLevel, this.thisType)
       : coreTypes = engine.coreTypes,
@@ -240,6 +242,10 @@ abstract class TypeInferrerImpl extends TypeInferrer {
         typeSchemaEnvironment = engine.typeSchemaEnvironment,
         isTopLevel = topLevel;
 
+  /// Indicates whether we are currently doing a "dry run" in order to collect
+  /// type inference dependencies.
+  bool get isDryRun => _dryRunDependencies != null;
+
   /// Gets the type promoter that should be used to promote types during
   /// inference.
   TypePromoter get typePromoter;
@@ -336,6 +342,14 @@ abstract class TypeInferrerImpl extends TypeInferrer {
     }
   }
 
+  /// Ends a dry run started by [startDryRun] and returns the collected
+  /// dependencies.
+  List<FieldNode> finishDryRun() {
+    var dryRunDependencies = _dryRunDependencies;
+    _dryRunDependencies = null;
+    return dryRunDependencies;
+  }
+
   FunctionType getCalleeFunctionType(Member interfaceMember,
       DartType receiverType, Name methodName, bool followCall) {
     var type = getCalleeType(interfaceMember, receiverType, methodName);
@@ -517,7 +531,8 @@ abstract class TypeInferrerImpl extends TypeInferrer {
       FunctionType calleeType, DartType returnType, Arguments arguments,
       {bool isOverloadedArithmeticOperator: false,
       DartType receiverType,
-      bool skipTypeArgumentInference: false}) {
+      bool skipTypeArgumentInference: false,
+      bool forceArgumentInference: false}) {
     var calleeTypeParameters = calleeType.typeParameters;
     List<DartType> explicitTypeArguments = getExplicitTypeArguments(arguments);
     bool inferenceNeeded = !skipTypeArgumentInference &&
@@ -558,8 +573,12 @@ abstract class TypeInferrerImpl extends TypeInferrer {
         DartType inferredFormalType = substitution != null
             ? substitution.substituteType(formalType)
             : formalType;
-        var expressionType = inferExpression(expression, inferredFormalType,
-            inferenceNeeded || isOverloadedArithmeticOperator);
+        var expressionType = inferExpression(
+            expression,
+            inferredFormalType,
+            inferenceNeeded ||
+                isOverloadedArithmeticOperator ||
+                forceArgumentInference);
         if (inferenceNeeded) {
           formalTypes.add(formalType);
           actualTypes.add(expressionType);
@@ -624,12 +643,28 @@ abstract class TypeInferrerImpl extends TypeInferrer {
   /// the statement type and calls the appropriate specialized "infer" method.
   void inferStatement(Statement statement);
 
+  /// Records that the field represented by [fieldNode] is a dependency of the
+  /// static field for which we are currently doing a dry run of type inference.
+  ///
+  /// May only be called if a dry run is in progress.
+  void recordDryRunDependency(FieldNode fieldNode) {
+    listener.recordDependency(fieldNode);
+    _dryRunDependencies.add(fieldNode);
+  }
+
   void recordNotImmediatelyEvident(int fileOffset) {
     assert(isTopLevel);
     isImmediatelyEvident = false;
     // TODO(paulberry): report an error.
   }
 
+  /// Begins a dry run of type inference, in which the goal is to collect the
+  /// dependencies of a given field.
+  void startDryRun() {
+    assert(_dryRunDependencies == null);
+    _dryRunDependencies = <FieldNode>[];
+  }
+
   DartType wrapFutureOrType(DartType type) {
     if (type is InterfaceType &&
         identical(type.classNode, coreTypes.futureOrClass)) {