Restore isNotEmpty and isNotBlank methods for non-nullable String receiver.

#KT-7234 Fixed

libraries/stdlib/src/kotlin/text/Strings.kt

@@ -1,6 +1,7 @@
 package kotlin
 
 import java.util.NoSuchElementException
+import kotlin.platform.platformName
 import kotlin.text.MatchResult
 import kotlin.text.Regex
 
@@ -149,6 +150,7 @@ public fun String.padEnd(length: Int, padChar: Char = ' '): String {
 
 /** Returns true if the string is not null and not empty */
 deprecated("Use !isNullOrEmpty() or isNullOrEmpty().not() for nullable strings.")
+platformName("isNotEmptyNullable")
 public fun String?.isNotEmpty(): Boolean = this != null && this.length() > 0
 
 /**
@@ -161,9 +163,20 @@ public fun String?.isNullOrEmpty(): Boolean = this == null || this.length() == 0
  */
 public fun String.isEmpty(): Boolean = length() == 0
 
+/**
+ * Returns `true` if this string is not empty.
+ */
+public fun String.isNotEmpty(): Boolean = length() > 0
+
 // implemented differently in JVM and JS
 //public fun String.isBlank(): Boolean = length() == 0 || all { it.isWhitespace() }
 
+
+/**
+ * Returns `true` if this string is not empty and contains some characters except of whitespace characters.
+ */
+public fun String.isNotBlank(): Boolean = !isBlank()
+
 /**
  * Returns `true` if this nullable string is either null or empty or consists solely of whitespace characters.
  */