Change IllegalArgumentException to ArgumentError.

lib/compiler/implementation/lib/coreimpl_patch.dart

Index: lib/compiler/implementation/lib/coreimpl_patch.dart
diff --git a/lib/compiler/implementation/lib/coreimpl_patch.dart b/lib/compiler/implementation/lib/coreimpl_patch.dart
index 4388dee2b4d5c83d6a24613d5fa4b101957f29c3..24ee7af9151c4f243ec9f1794035f89a4804a5ea 100644
--- a/lib/compiler/implementation/lib/coreimpl_patch.dart
+++ b/lib/compiler/implementation/lib/coreimpl_patch.dart
@@ -11,7 +11,7 @@ patch class StringImplementation {
   patch static _fromCharCodes(List<int> charCodes) {
     checkNull(charCodes);
     if (!isJsArray(charCodes)) {
-      if (charCodes is !List) throw new IllegalArgumentException(charCodes);
+      if (charCodes is !List) throw new ArgumentError(charCodes);
       charCodes = new List.from(charCodes);
     }
     return Primitives.stringFromCharCodes(charCodes);
@@ -20,7 +20,7 @@ patch class StringImplementation {
   patch String join(List<String> strings, String separator) {
     checkNull(strings);
     checkNull(separator);
-    if (separator is !String) throw new IllegalArgumentException(separator);
+    if (separator is !String) throw new ArgumentError(separator);
     return stringJoinUnchecked(_toJsStringArray(strings), separator);
   }
 
@@ -37,14 +37,14 @@ patch class StringImplementation {
       for (int i = 0; i < length; i++) {
         final string = strings[i];
         checkNull(string);
-        if (string is !String) throw new IllegalArgumentException(string);
+        if (string is !String) throw new ArgumentError(string);
       }
     } else {
       array = new List(length);
       for (int i = 0; i < length; i++) {
         final string = strings[i];
         checkNull(string);
-        if (string is !String) throw new IllegalArgumentException(string);
+        if (string is !String) throw new ArgumentError(string);
         array[i] = string;
       }
     }