Support creating flexible types in tests

Flexible types can not be created in normal user code, but if there's a special classifier `kotlin.internal.flexible.ft` with two type parameters,
its occurrences are replaced by flexible types, e.g. `ft<Int, Int?>` becomes `Int!`

generators/src/org/jetbrains/jet/generators/injectors/GenerateInjectors.kt

@@ -41,6 +41,7 @@ import org.jetbrains.jet.lang.resolve.java.lazy.SingleModuleClassResolver
 import org.jetbrains.jet.lang.resolve.kotlin.VirtualFileFinderFactory
 import org.jetbrains.jet.lang.resolve.java.TopDownAnalyzerFacadeForJVM
 import org.jetbrains.jet.lang.resolve.kotlin.JavaDeclarationCheckerProvider
+import org.jetbrains.jet.lang.resolve.java.JavaFlexibleTypeCapabilitiesProvider
 
 // NOTE: After making changes, you need to re-generate the injectors.
 //       To do that, you can run main in this file.
@@ -120,7 +121,8 @@ private fun generatorForTopDownAnalyzerForJvm() =
                     javaClass<MutablePackageFragmentProvider>(),
                     javaClass<JavaPropertyInitializerEvaluatorImpl>(),
                     javaClass<JavaSourceElementFactoryImpl>(),
-                    javaClass<SingleModuleClassResolver>()
+                    javaClass<SingleModuleClassResolver>(),
+                    javaClass<JavaFlexibleTypeCapabilitiesProvider>()
             )
             field(javaClass<VirtualFileFinder>(), init = GivenExpression(javaClass<VirtualFileFinder>().getName() + ".SERVICE.getInstance(project)"))
         }
@@ -185,7 +187,8 @@ private fun generatorForLazyResolveWithJava() =
                     javaClass<PsiBasedMethodSignatureChecker>(),
                     javaClass<PsiBasedExternalAnnotationResolver>(),
                     javaClass<JavaPropertyInitializerEvaluatorImpl>(),
-                    javaClass<JavaSourceElementFactoryImpl>()
+                    javaClass<JavaSourceElementFactoryImpl>(),
+                    javaClass<JavaFlexibleTypeCapabilitiesProvider>()
             )
             field(javaClass<AdditionalCheckerProvider>(),
                   init = GivenExpression(javaClass<JavaDeclarationCheckerProvider>().getName() + ".INSTANCE$"))