Make CharSequence.length a function instead of property

And String.length as well.

This is done for JVM interoperability: java.lang.CharSequence is an open class
and has a function 'length()' which should be implemented in subclasses
somehow.

A minor unexpected effect of this is that String.length() is now a compile-time
constant (it wasn't such as a property because properties are not supported in
compile-time constant evaluation)

 #KT-3571 Fixed

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KTopLevelExtensionPropertyImpl.kt

@@ -95,8 +95,8 @@ private fun mapJavaClassToKotlin(name: String): String {
         }
     }
     if (name[0] == '[') {
-        val element = (name as java.lang.String).substring(1)
-        return when (element[0]) {
+        val element = (name as java.lang.String).substring(1) as java.lang.String
+        return when (element.charAt(0)) {
             'Z' -> "kotlin.BooleanArray"
             'C' -> "kotlin.CharArray"
             'B' -> "kotlin.ByteArray"
@@ -105,8 +105,8 @@ private fun mapJavaClassToKotlin(name: String): String {
             'F' -> "kotlin.FloatArray"
             'J' -> "kotlin.LongArray"
             'D' -> "kotlin.DoubleArray"
-            'L' -> "kotlin.Array<${mapJavaClassToKotlin((element as java.lang.String).substring(1, element.length() - 1))}>"
-            else -> "kotlin.Array<${mapJavaClassToKotlin(element)}>"
+            'L' -> "kotlin.Array<${mapJavaClassToKotlin(element.substring(1, element.length() - 1))}>"
+            else -> "kotlin.Array<${mapJavaClassToKotlin(element as kotlin.String)}>"
         }
     }
     return name

core/reflection.jvm/src/kotlin/reflect/jvm/internal/util.kt

@@ -24,7 +24,7 @@ suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
 private fun String.capitalizeWithJavaBeanConvention(): String {
     // The code is a bit crooked because otherwise there are overload resolution ambiguities caused by the fact
     // that we compile it with the built-ins both in source and as a compiled library
-    val l = length
+    val l = length()
     if (l > 1 && Character.isUpperCase(get(1))) return this
     val first = get(0)
     this as java.lang.String