Implement hack to support both remove() and removeAt() in MutableList<Int>

Also add couple of tests about CharSequence.get

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/builtinsPropertiesUtil.kt

@@ -115,11 +115,13 @@ public fun CallableMemberDescriptor.getJvmMethodNameIfSpecial(): String? {
 private fun CallableMemberDescriptor.getBuiltinOverriddenThatAffectsJvmName(): CallableMemberDescriptor? {
     val overriddenBuiltin = getBuiltinSpecialOverridden() ?: return null
 
-    if (isFromJava || isFromBuiltins()) return overriddenBuiltin
+    if (isFromJavaOrBuiltins()) return overriddenBuiltin
 
     return null
 }
 
+fun CallableMemberDescriptor.isFromJavaOrBuiltins() = isFromJava || isFromBuiltins()
+
 private fun CallableMemberDescriptor.specialJvmName(): Name? {
     return BuiltinSpecialMethods.FQ_NAMES_TO_JVM_MAP[fqNameOrNull() ?: return null]
 }