Loading functions from superclasses before current to avoid heisenbug.

Added test with two supertypes.

 #KT-2776 in progress

compiler/testData/loadJavaCustom/kotlinSignature/TwoSuperclassesInconsistentGenericTypes.java

@@ -0,0 +1,22 @@
+package test;
+
+import org.jetbrains.annotations.NotNull;
+import java.util.List;
+
+import jet.runtime.typeinfo.KotlinSignature;
+
+public interface TwoSuperclassesInconsistentGenericTypes {
+    @KotlinSignature("fun foo(): MutableList<String?>")
+    List<String> foo();
+
+    public interface Other {
+        @KotlinSignature("fun foo(): MutableList<String>?")
+        List<String> foo();
+    }
+
+    public class Sub implements TwoSuperclassesInconsistentGenericTypes, Other {
+        public List<String> foo() {
+            throw new UnsupportedOperationException();
+        }
+    }
+}

compiler/testData/loadJavaCustom/kotlinSignature/TwoSuperclassesInconsistentGenericTypes.txt

@@ -0,0 +1,12 @@
+namespace test
+
+public abstract trait test.TwoSuperclassesInconsistentGenericTypes : java.lang.Object {
+    public abstract fun foo(): jet.MutableList<jet.String?>
+    public abstract trait test.TwoSuperclassesInconsistentGenericTypes.Other : java.lang.Object {
+        public abstract fun foo(): jet.MutableList<jet.String>?
+    }
+    public open class test.TwoSuperclassesInconsistentGenericTypes.Sub : test.TwoSuperclassesInconsistentGenericTypes, test.TwoSuperclassesInconsistentGenericTypes.Other {
+        public final /*constructor*/ fun <init>(): test.TwoSuperclassesInconsistentGenericTypes.Sub
+        public open override /*2*/ fun foo(): jet.MutableList<jet.String?>
+    }
+}