[IR Test] Properly create empty dump for IR files witout source

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/DumpIrTree.kt

@@ -37,12 +37,13 @@ fun IrElement.dump(normalizeNames: Boolean = false, stableOrder: Boolean = false
     }
 
 fun IrFile.dumpTreesFromLineNumber(lineNumber: Int, normalizeNames: Boolean = false): String {
+    if (shouldSkipDump()) return ""
     val sb = StringBuilder()
     accept(DumpTreeFromSourceLineVisitor(fileEntry, lineNumber, sb, normalizeNames), null)
     return sb.toString()
 }
 
-fun IrFile.shouldSkipDump(): Boolean {
+private fun IrFile.shouldSkipDump(): Boolean {
     val entry = fileEntry as? NaiveSourceBasedFileEntryImpl ?: return false
     return entry.lineStartOffsetsAreEmpty
 }

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/backend/handlers/IrTextDumpHandler.kt

@@ -65,7 +65,6 @@ class IrTextDumpHandler(testServices: TestServices) : AbstractIrHandler(testServ
         val builder = baseDumper.builderForModule(module)
         for ((testFile, irFile) in testFileToIrFile) {
             if (testFile?.directives?.contains(EXTERNAL_FILE) == true) continue
-            if (irFile.shouldSkipDump()) continue
             var actualDump = irFile.dumpTreesFromLineNumber(lineNumber = 0, normalizeNames = true)
             if (actualDump.isEmpty()) {
                 actualDump = irFile.dumpTreesFromLineNumber(lineNumber = UNDEFINED_OFFSET, normalizeNames = true)

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/backend/handlers/IrTreeVerifierHandler.kt

@@ -8,7 +8,6 @@ package org.jetbrains.kotlin.test.backend.handlers
 import org.jetbrains.kotlin.ir.IrVerifier
 import org.jetbrains.kotlin.ir.util.deepCopyWithSymbols
 import org.jetbrains.kotlin.ir.util.dumpTreesFromLineNumber
-import org.jetbrains.kotlin.ir.util.shouldSkipDump
 import org.jetbrains.kotlin.test.backend.handlers.IrTextDumpHandler.Companion.groupWithTestFiles
 import org.jetbrains.kotlin.test.backend.ir.IrBackendInput
 import org.jetbrains.kotlin.test.directives.CodegenTestDirectives
@@ -30,7 +29,6 @@ class IrTreeVerifierHandler(testServices: TestServices) : AbstractIrHandler(test
 
             IrVerifier(assertions).verifyWithAssert(irFile)
 
-            if (irFile.shouldSkipDump()) continue
             val actualDump = irFile.dumpTreesFromLineNumber(lineNumber = 0, normalizeNames = true)
 
             val irFileCopy = irFile.deepCopyWithSymbols()