Introduce experimental -Xuse-javac compilation mode

In this mode, javac AST and Symbol files are used during
Kotlin compilation instead of PSI / binary stuff.
Later, they are reused for Java file compilation.
javac in this mode is integrated into kotlinc.

generators/src/org/jetbrains/kotlin/generators/tests/GenerateTests.kt

@@ -345,7 +345,12 @@ fun main(args: Array<String>) {
         }
 
         testClass<AbstractCompileJavaAgainstKotlinTest> {
-            model("compileJavaAgainstKotlin")
+            model("compileJavaAgainstKotlin", testClassName = "WithoutJavac", testMethod = "doTestWithoutJavac")
+            model("compileJavaAgainstKotlin", testClassName = "WithJavac", testMethod = "doTestWithJavac")
+        }
+
+        testClass<AbstractCompileKotlinAgainstJavaTest> {
+            model("compileKotlinAgainstJava")
         }
 
         testClass<AbstractCompileKotlinAgainstKotlinTest> {