Fix crashes in String natives.

tests/co19/co19-runtime.status

Index: tests/co19/co19-runtime.status
===================================================================
--- tests/co19/co19-runtime.status	(revision 1173)
+++ tests/co19/co19-runtime.status	(working copy)
@@ -18,6 +18,7 @@
 LibTest/core/double/operatorDivision/double/operatorDivision/A01/t05: Fail  # Issue 7
 LibTest/core/double/operator~div/double/operator~div/A01/t05: Fail  # Issue 7
 LibTest/core/Math/atan2/Math/atan2/A01/t03: Fail  # Issue 8
+LibTest/core/String/charCodeAt/String/charCodeAt/A03/t01: Fail  # Issue 9
 
 LangGuideTest/02_Language_Constructs/02_1_Class/02_1_Class_Const_Expressions/A04/t01: Fail # Bug 5371433
 LangGuideTest/02_Language_Constructs/02_1_Class/02_1_Class_Construction/A10/t01: Fail # Bug 5371433
@@ -48,16 +49,11 @@
 LibTest/core/RegExp/firstMatch/Pattern_semantics/15.10.2.15_NonEmptyClassRanges/RegExp/firstMatch/NonEmptyClassRanges/A01/t01: Fail
 LibTest/core/Set/filter/Set/filter/A01/t03: Fail
 LibTest/core/Set/forEach/Set/forEach/A01/t03: Fail
-LibTest/core/String/charCodeAt/String/charCodeAt/A02/t01: Crash
-LibTest/core/String/charCodeAt/String/charCodeAt/A03/t01: Crash
 LibTest/core/String/contains/String/contains/A02/t01: Fail
-LibTest/core/String/operator\[]/String/operator\[]/A02/t01: Crash
 LibTest/core/String/replaceAll/String/replaceAll/A01/t01: Fail
 LibTest/core/String/split/String/split/A01/t01: Fail
 LibTest/core/String/split/String/split/A01/t02: Fail
 LibTest/core/String/trim/String/trim/A01/t02: Fail
-LibTest/core/Strings/concatAll/Strings/concatAll/A01/t02: Crash
-LibTest/core/Strings/join/Strings/join/A01/t02: Crash
 
 
 # New failures
@@ -103,8 +99,7 @@
 [ $component == vm && $mode == debug && $unchecked ]
 LibTest/core/Isolate/spawn/Isolate/spawn/A01/t12: Pass || Timeout
 [ $component == vm && $mode == release ]
-LibTest/core/List/copyFrom/List/copyFrom/A01/t03: Fail
-LibTest/core/List/copyFrom/List/copyFrom/A01/t04: Fail
+
 [ $component == vm ]
 LangSpecTest/13_Types/13_2_Dynamic_Type_System/A01/t01: Fail
 LangSpecTest/13_Types/13_4_Interface_Types/A07/t02: Fail
@@ -213,8 +208,6 @@
 LibTest/core/StopWatch/stop/StopWatch/stop/A01/t01: Fail
 LibTest/core/String/replaceFirst/String/replaceFirst/A01/t01: Fail
 LibTest/core/StringBuffer/add/StringBuffer/add/A02/t01: Fail
-LibTest/core/Strings/concatAll/Strings/concatAll/A03/t01: crash
-LibTest/core/Strings/join/Strings/join/A03/t01: crash
 LibTest/core/TypeError/srcType/TypeError/srcType/A01/t01: Fail
 LibTest/core/double/isOdd/double/isOdd/A01/t02: Fail
 LibTest/core/double/operator%/double/operator%/A01/t06: Fail