FIR IDE: add tests for completion weighers from old testdata

idea/idea-completion/testData/weighers/basic/Prefix.kt

@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun shouldCompleteTopLevelCallablesFromIndex() = true
 
 fun foo(statement: String) {

idea/idea-completion/testData/weighers/basic/expectedInfo/ExpectedType2.kt

@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 interface I {
     fun takeXxx(): Int = 0
     fun takeYyy(): String = ""

idea/idea-completion/tests/org/jetbrains/kotlin/idea/completion/test/weighers/AbstractCompletionWeigherTest.kt

@@ -28,11 +28,17 @@ abstract class AbstractCompletionWeigherTest(val completionType: CompletionType,
         val items = InTextDirectivesUtils.findArrayWithPrefixes(text, "// ORDER:")
         Assert.assertTrue("""Some items should be defined with "// ORDER:" directive""", items.isNotEmpty())
 
-        withCustomCompilerOptions(text, project, module) {
-            myFixture.complete(completionType, InTextDirectivesUtils.getPrefixedInt(text, "// INVOCATION_COUNT:") ?: 1)
-            myFixture.assertPreferredCompletionItems(InTextDirectivesUtils.getPrefixedInt(text, "// SELECTED:") ?: 0, *items)
+        executeTest {
+            withCustomCompilerOptions(text, project, module) {
+                myFixture.complete(completionType, InTextDirectivesUtils.getPrefixedInt(text, "// INVOCATION_COUNT:") ?: 1)
+                myFixture.assertPreferredCompletionItems(InTextDirectivesUtils.getPrefixedInt(text, "// SELECTED:") ?: 0, *items)
+            }
         }
     }
+
+    open fun executeTest(test: () -> Unit) {
+        test()
+    }
 }
 
 abstract class AbstractBasicCompletionWeigherTest() : AbstractCompletionWeigherTest(CompletionType.BASIC, "weighers/basic") {