Run K2 scripts in PSI mode

compiler/testData/integration/ant/jvm/forkOnError/build.log.expected

@@ -9,6 +9,15 @@ build:
   [kotlinc] Compiling [[TestData]] => [[Temp]/fork.jar]
   [kotlinc] -Xms64m
   [kotlinc] -Xmx128m
+  [kotlinc] warning: ATTENTION!
+  [kotlinc] This build uses unsafe internal compiler arguments:
+  [kotlinc]
+  [kotlinc] -XXLanguage:+EnableDfaWarningsInK2
+  [kotlinc]
+  [kotlinc] This mode is not recommended for production use,
+  [kotlinc] as no stability/compatibility guarantees are given on
+  [kotlinc] compiler or generated code. Use it at your own risk!
+  [kotlinc]
   [kotlinc] error: warnings found and -Werror specified
   [kotlinc] [TestData]/test.kt:4:15: warning: this cast can never succeed
   [kotlinc]     println(0 as String)

compiler/testData/integration/ant/jvm/forkOnError/build.xml

@@ -20,6 +20,8 @@
             <jvmarg value="-Xmx128m"/>
             <jvmarg value="-javaagent:${temp}/premain.jar"/>
             <compilerarg value="-Werror"/>
+            <compilerarg line="-Xuse-fir-lt=false"/>
+            <compilerarg line="-XXLanguage:+EnableDfaWarningsInK2"/>
         </kotlinc>
     </target>
 </project>