[dart2wasm] Fix JSCM String.fromCharCodes

Fixes test corelib/string_fromcharcodes_test in JSCM.

Change-Id: I9c2a1b7f67819c193a98b00932328571303589fb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/392901
Commit-Queue: Ömer Ağacan <[email protected]>
Reviewed-by: Slava Egorov <[email protected]>

Author: osa1

sdk/lib/_internal/wasm_js_compatibility/lib/string_patch.dart

@@ -15,12 +15,12 @@ class String {
   @patch
   factory String.fromCharCodes(Iterable<int> charCodes,
       [int start = 0, int? end]) {
-    final length = charCodes.length;
-
-    RangeError.checkValueInInterval(start, 0, length);
-
+    RangeError.checkNotNegative(start, "start");
     if (end != null) {
-      RangeError.checkValueInInterval(end, start, length);
+      if (end < start) {
+        throw RangeError.range(end, start, null, "end");
+      }
+      if (end == start) return "";
     }
 
     // Skip until `start`.
@@ -32,14 +32,15 @@ class String {
     // The part of the iterable converted to string is collected in a JS typed
     // array, to be able to effciently get subarrays, to pass to
     // `String.fromCharCode.apply`.
-    final charCodesLength = (end ?? length) - start;
+    final charCodesLength = (end ?? charCodes.length) - start;
+    if (charCodesLength <= 0) return "";
     final typedArrayLength = charCodesLength * 2;
     final list = JSUint32ArrayImpl(typedArrayLength);
     int index = 0; // index in `list`.
     end ??= start + charCodesLength;
     for (int i = start; i < end; i++) {
       if (!it.moveNext()) {
-        throw RangeError.range(end, start, i);
+        break;
       }
       final charCode = it.current;
       if (charCode >= 0 && charCode <= 0xffff) {