String.toBoolean() should be String?.toBoolean() #KT-14119

libraries/stdlib/common/src/kotlin/TextH.kt

@@ -5,6 +5,8 @@
 
 package kotlin.text
 
+import kotlin.internal.LowPriorityInOverloadResolution
+
 expect class Regex {
     constructor(pattern: String)
     constructor(pattern: String, option: RegexOption)
@@ -282,9 +284,17 @@ public expect val String.Companion.CASE_INSENSITIVE_ORDER: Comparator<String>
 
 
 /**
- * Returns `true` if the contents of this string is equal to the word "true", ignoring case, and `false` otherwise.
+ * Returns `true` if the content of this string is equal to the word "true", ignoring case, and `false` otherwise.
  */
-expect fun String.toBoolean(): Boolean
+@LowPriorityInOverloadResolution
+@kotlin.internal.InlineOnly
+public inline fun String.toBoolean(): Boolean = this.toBoolean()
+
+/**
+ * Returns `true` if this string is not `null` and its content is equal to the word "true", ignoring case, and `false` otherwise.
+ */
+@SinceKotlin("1.4")
+public expect fun String?.toBoolean(): Boolean
 
 /**
  * Parses the string as a signed [Byte] number and returns the result.