Minor. Split ExpressionReceiver to interface & implementation

compiler/backend/src/org/jetbrains/kotlin/codegen/FunctionReferenceGenerationStrategy.java

@@ -167,7 +167,7 @@ public class FunctionReferenceGenerationStrategy extends FunctionGenerationStrat
         KtExpression receiverExpression = KtPsiFactoryKt
                 .KtPsiFactory(state.getProject()).createExpression("callableReferenceFakeReceiver");
         codegen.tempVariables.put(receiverExpression, receiverParameterStackValue(signature));
-        return new ExpressionReceiver(receiverExpression, receiver.getType());
+        return new ExpressionReceiver.Companion.ExpressionReceiverImpl(receiverExpression, receiver.getType());
     }
 
     @NotNull

compiler/frontend/src/org/jetbrains/kotlin/resolve/scopes/receivers/ExpressionReceiver.kt

@@ -20,17 +20,22 @@ import org.jetbrains.kotlin.psi.KtExpression
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.types.KotlinType
 
-class ExpressionReceiver(val expression: KtExpression, type: KotlinType) : AbstractReceiverValue(type), ReceiverValue {
+interface ExpressionReceiver :  ReceiverValue {
-
+    val expression: KtExpression
-    override fun toString() = "$type {$expression: ${expression.text}}"
 
     companion object {
+        class ExpressionReceiverImpl(
+                override val expression: KtExpression, type: KotlinType
+        ): AbstractReceiverValue(type), ExpressionReceiver {
+            override fun toString() = "$type {$expression: ${expression.text}}"
+        }
 
         fun create(
                 expression: KtExpression,
                 type: KotlinType,
-                bindingContext: BindingContext): ExpressionReceiver {
+                bindingContext: BindingContext
-            return ExpressionReceiver(expression, type)
+        ): ExpressionReceiver {
+            return ExpressionReceiverImpl(expression, type)
         }
     }
 }

compiler/tests/org/jetbrains/kotlin/types/KotlinTypeCheckerTest.java

@@ -558,7 +558,7 @@ public class KotlinTypeCheckerTest extends KotlinLiteFixture {
         KotlinType thisType = makeType(contextType);
         ReceiverParameterDescriptorImpl receiverParameterDescriptor = new ReceiverParameterDescriptorImpl(
                 scopeWithImports.getOwnerDescriptor(),
-                new ExpressionReceiver(KtPsiFactoryKt.KtPsiFactory(getProject()).createExpression(expression), thisType)
+                new ExpressionReceiver.Companion.ExpressionReceiverImpl(KtPsiFactoryKt.KtPsiFactory(getProject()).createExpression(expression), thisType)
         );
 
         LexicalScope scope = new LexicalScopeImpl(scopeWithImports, scopeWithImports.getOwnerDescriptor(), false,