[FIR] Fix calculating offsets of light tree source elements for local declarations

compiler/fir/raw-fir/light-tree2fir/src/org/jetbrains/kotlin/fir/lightTree/converter/BaseConverter.kt

@@ -126,6 +126,16 @@ abstract class BaseConverter(
         return tree.getParent(this)
     }
 
+    fun LighterASTNode.getParents(): Sequence<LighterASTNode> {
+        var node = this
+        return sequence {
+            while (true) {
+                yield(node)
+                node = node.getParent() ?: break
+            }
+        }
+    }
+
     fun LighterASTNode?.getChildNodesByType(type: IElementType): List<LighterASTNode> {
         return this?.forEachChildrenReturnList { node, container ->
             when (node.tokenType) {

compiler/fir/raw-fir/light-tree2fir/src/org/jetbrains/kotlin/fir/lightTree/converter/DeclarationsConverter.kt

@@ -1410,7 +1410,7 @@ class DeclarationsConverter(
         return if (!stubMode) {
             val blockTree = LightTree2Fir.buildLightTreeBlockExpression(block.asText)
             return DeclarationsConverter(
-                baseSession, baseScopeProvider, stubMode, blockTree, offset = tree.getStartOffset(block), context
+                baseSession, baseScopeProvider, stubMode, blockTree, offset = offset + tree.getStartOffset(block), context
             ).convertBlockExpression(blockTree.root)
         } else {
             val firExpression = buildExpressionStub()