[Wasm] Improve string constructor in stdlib

libraries/stdlib/wasm/internal/kotlin/wasm/internal/ExternalWrapper.kt

@@ -147,7 +147,7 @@ internal fun convertJsStringToKotlinString(x: ExternalInterfaceType): String {
     val length = stringLength(x)
     val addr = unsafeGetScratchRawMemory(INT_SIZE_BYTES + length * CHAR_SIZE_BYTES)
     jsWriteStringIntoMemory(x, addr)
-    return kotlin.String(unsafeRawMemoryToCharArray(addr, length))
+    return String.unsafeFromCharArray(unsafeRawMemoryToCharArray(addr, length))
 }
 
 

libraries/stdlib/wasm/internal/kotlin/wasm/internal/Number2String.kt

@@ -64,7 +64,7 @@ internal fun itoa32(inputValue: Int, radix: Int): String {
     if (sign == 1)
         buf[0] = CharCodes.MINUS.code.toChar()
 
-    return kotlin.String(buf)
+    return String.unsafeFromCharArray(buf)
 }
 
 private fun utoaDecSimple(buffer: CharArray, numInput: Int, offsetInput: Int) {
@@ -144,7 +144,7 @@ internal fun itoa64(inputValue: Long, radix: Int): String {
     if (sign == 1)
         buf[0] = CharCodes.MINUS.code.toChar()
 
-    return kotlin.String(buf)
+    return String.unsafeFromCharArray(buf)
 }
 
 // Count number of decimals for u64 values
@@ -178,7 +178,7 @@ internal fun dtoa(value: Double): String {
     val size = dtoaCore(buf, value)
     val ret = CharArray(size)
     buf.copyInto(ret, 0, 0, size)
-    return kotlin.String(ret)
+    return String.unsafeFromCharArray(ret)
 }
 
 private fun dtoaCore(buffer: CharArray, valueInp: Double): Int {