Update maxStack on synthetic instruction insertion

#KT-19723 Fixed

compiler/testData/codegen/boxInline/anonymousObject/kt19723.kt

@@ -0,0 +1,21 @@
+// FILE: 1.kt
+package test
+
+inline fun String.fire(message: String? = null) {
+    val res = this + message!!
+}
+
+// FILE: 2.kt
+// NO_CHECK_LAMBDA_INLINING
+
+import test.*
+
+fun box(): String {
+    val receiver = "receiver"
+    "".let {
+        {
+            receiver.fire()
+        }
+    }
+    return "OK"
+}