Minor, fix warnings on new stdlib API

In modules where allWarningsAsErrors is not yet enabled.

libraries/stdlib/js/src/kotlin/text/stringsCode.kt

@@ -85,7 +85,7 @@ public actual fun CharSequence.regionMatches(thisOffset: Int, other: CharSequenc
 @Deprecated("Use replaceFirstChar instead.", ReplaceWith("replaceFirstChar { if (it.isLowerCase()) it.titlecase() else it.toString() }"))
 @DeprecatedSinceKotlin(warningSince = "1.5")
 public actual fun String.capitalize(): String {
-    return if (isNotEmpty()) substring(0, 1).toUpperCase() + substring(1) else this
+    return if (isNotEmpty()) substring(0, 1).uppercase() + substring(1) else this
 }
 
 /**
@@ -97,7 +97,7 @@ public actual fun String.capitalize(): String {
 @Deprecated("Use replaceFirstChar instead.", ReplaceWith("replaceFirstChar { it.lowercase() }"))
 @DeprecatedSinceKotlin(warningSince = "1.5")
 public actual fun String.decapitalize(): String {
-    return if (isNotEmpty()) substring(0, 1).toLowerCase() + substring(1) else this
+    return if (isNotEmpty()) substring(0, 1).lowercase() + substring(1) else this
 }
 
 /**

libraries/stdlib/test/collections/SequenceTest.kt

@@ -122,7 +122,7 @@ public class SequenceTest {
         data.forEach {  }
         assertEquals(0, count, "onEach should be executed only when resulting sequence is iterated")
 
-        val sum = newData.sumBy { it.length }
+        val sum = newData.sumOf { it.length }
         assertEquals(sum, count)
     }