Debugger: Generate line numbers for class initializers with a number on the 'init' keyword (KT-16277)

Debugger tests not absent as they use the bootstrap version of kotlinc.
Obviously, this change is not present in it yet.

compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java

@@ -1473,7 +1473,7 @@ public class ExpressionCodegen extends KtVisitor<StackValue, StackValue> impleme
         markLineNumber(element, false);
     }
 
-    public void markLineNumber(@NotNull KtElement statement, boolean markEndOffset) {
+    public void markLineNumber(@NotNull PsiElement statement, boolean markEndOffset) {
         if (!shouldMarkLineNumbers) return;
 
         Integer lineNumber = CodegenUtil.getLineNumberForElement(statement, markEndOffset);

compiler/backend/src/org/jetbrains/kotlin/codegen/MemberCodegen.java

@@ -507,9 +507,18 @@ public abstract class MemberCodegen<T extends KtPureElement/* TODO: & KtDeclarat
                     if (i == declarations.size() - 1 && this instanceof ScriptCodegen) {
                         bodyExpressionType = expressionCodegen.expressionType(body);
                     }
+
+                    if (declaration instanceof KtClassInitializer) {
+                        KtClassInitializer classInitializer = (KtClassInitializer) declaration;
+                        expressionCodegen.markLineNumber(classInitializer.getInitKeyword(), true);
+                        expressionCodegen.v.nop();
+                    }
+
                     expressionCodegen.gen(body, bodyExpressionType);
-                    expressionCodegen.markLineNumber(declaration, true);
-                    nopSeparatorNeeded = true;
+                    if (declaration instanceof KtClassInitializer) {
+                        expressionCodegen.markLineNumber(declaration, true);
+                        nopSeparatorNeeded = true;
+                    }
                 }
             }
         }