Fix generation of JS source maps for synthetic code in constructors

js/js.translator/testData/lineNumbers/syntheticCodeInConstructors.kt

@@ -0,0 +1,28 @@
+object O {
+    init {
+        println()
+    }
+}
+
+open class A(x: Int)
+
+class B :
+        A(
+                23
+        )
+
+class C : A {
+    constructor(x: Int) :
+        super(
+                x
+        ) {
+        println()
+    }
+
+    constructor() :
+            this (
+                    42
+            )
+}
+
+// LINES: 1 3 * 10 11 * 15 16 17 14 19 15 22 23 24 22