add a few lexer testcases (related to json parsing)

testcases/test-lex-line-continuation.js

@@ -0,0 +1,19 @@
+
+/*===
+"This is a \
+line continuation."
+This is a line continuation.
+===*/
+
+/* Line continuation inside a string. */
+
+var str;
+
+try {
+    str = '"This is a \\\nline continuation."';
+    print(str);
+    print(eval(str));
+} catch (e) {
+    print(e.name);
+}
+

testcases/test-lex-unterminated-hex-uni-escape.js

@@ -0,0 +1,80 @@
+/*===
+\u
+1 u
+\u1
+2 u1
+\u12
+3 u12
+\u123
+4 u123
+\u123G
+5 u123G
+\x
+1 x
+\x1
+2 x1
+\x1G
+3 x1G
+===*/
+
+/* Unterminated hex or unicode escapes should apparently (?) be parsed with
+ * the longest match principle at least inside string literals.
+ *
+ * In other words, if the string ends or the escape is otherwise invalid,
+ * the escape characters should be parsed as itself: "\uX" -> "uX".
+ *
+ * Both V8 and Rhino parse these without a SyntaxError.
+ */
+
+function testString(x) {
+    var t;
+
+    print(x);
+    var t = eval('"' + x + '"');
+    print(t.length, t);
+}
+
+function testStrings() {
+    var strings = [
+        '\\u',
+        '\\u1',
+        '\\u12',
+        '\\u123',
+        '\\u123G',
+        '\\x',
+        '\\x1',
+        '\\x1G',
+    ];
+    var i;
+
+    for (i = 0; i < strings.length; i++) {
+        try {
+            testString(strings[i]);
+        } catch (e) {
+            print(e);
+        }
+    }
+}
+
+
+try {
+    testStrings();
+} catch (e) {
+    print(e.name);
+}
+
+/*===
+SyntaxError
+===*/
+
+/* However, an unterminated unicode escape outside a string literal
+ * won't be parsed by V8 or Rhino if it is broken.
+ */
+
+try {
+    // if "\u" parsed as "u", same as assignemtn:  u123 = 1
+    print(eval('\\u123 = 1;'));
+} catch (e) {
+    print(e.name);
+}
+