Clarify floating-point to integral conversion rounding behaviour

libraries/stdlib/js-ir/runtime/longjs.kt

@@ -336,7 +336,7 @@ internal fun fromInt(value: Int) = Long(value, if (value < 0) -1 else 0)
 
 /**
  * Converts this [Double] value to [Long].
- * The fractional part, if any, is rounded down.
+ * The fractional part, if any, is rounded down towards zero.
  * Returns zero if this `Double` value is `NaN`, [Long.MIN_VALUE] if it's less than `Long.MIN_VALUE`,
  * [Long.MAX_VALUE] if it's bigger than `Long.MAX_VALUE`.
  */

libraries/stdlib/js-v1/src/js/long.js

@@ -95,7 +95,7 @@ Kotlin.Long.fromInt = function(value) {
 
 /**
  * Converts this number value to `Long`.
- * The fractional part, if any, is rounded down.
+ * The fractional part, if any, is rounded down towards zero.
  * Returns zero if this `Double` value is `NaN`, `Long.MIN_VALUE` if it's less than `Long.MIN_VALUE`,
  * `Long.MAX_VALUE` if it's bigger than `Long.MAX_VALUE`.
  * @param {number} value The number in question.

libraries/stdlib/unsigned/src/kotlin/UInt.kt

@@ -313,7 +313,7 @@ public inline fun Long.toUInt(): UInt = UInt(this.toInt())
 /**
  * Converts this [Float] value to [UInt].
  *
- * The fractional part, if any, is rounded down.
+ * The fractional part, if any, is rounded down towards zero.
  * Returns zero if this `Float` value is negative or `NaN`, [UInt.MAX_VALUE] if it's bigger than `UInt.MAX_VALUE`.
  */
 @SinceKotlin("1.3")
@@ -323,7 +323,7 @@ public inline fun Float.toUInt(): UInt = doubleToUInt(this.toDouble())
 /**
  * Converts this [Double] value to [UInt].
  *
- * The fractional part, if any, is rounded down.
+ * The fractional part, if any, is rounded down towards zero.
  * Returns zero if this `Double` value is negative or `NaN`, [UInt.MAX_VALUE] if it's bigger than `UInt.MAX_VALUE`.
  */
 @SinceKotlin("1.3")

libraries/stdlib/unsigned/src/kotlin/ULong.kt

@@ -316,7 +316,7 @@ public inline fun Long.toULong(): ULong = ULong(this)
 /**
  * Converts this [Float] value to [ULong].
  *
- * The fractional part, if any, is rounded down.
+ * The fractional part, if any, is rounded down towards zero.
  * Returns zero if this `Float` value is negative or `NaN`, [ULong.MAX_VALUE] if it's bigger than `ULong.MAX_VALUE`.
  */
 @SinceKotlin("1.3")
@@ -326,7 +326,7 @@ public inline fun Float.toULong(): ULong = doubleToULong(this.toDouble())
 /**
  * Converts this [Double] value to [ULong].
  *
- * The fractional part, if any, is rounded down.
+ * The fractional part, if any, is rounded down towards zero.
  * Returns zero if this `Double` value is negative or `NaN`, [ULong.MAX_VALUE] if it's bigger than `ULong.MAX_VALUE`.
  */
 @SinceKotlin("1.3")