Ensure Array.prototype.indexOf returns +0 rather than -0

A recent ES2016 draft spec clarification indicates that, if -0 is
passed into Array.prototype.indexOf or Array.prototype.lastIndexOf
as the starting index, and the result is found at index 0, then +0
rather than -0 should be returned. This patch ensures that V8 has
that result, which is consistent with what some other browsers
return. The patch allows a couple test262 tests to pass.

R=adamk
LOG=Y

Review URL: https://codereview.chromium.org/1729653002

Cr-Commit-Position: refs/heads/master@{#34229}

src/js/array.js

@@ -1347,7 +1347,7 @@ function InnerArrayIndexOf(array, element, index, length) {
   if (IS_UNDEFINED(index)) {
     index = 0;
   } else {
-    index = TO_INTEGER(index);
+    index = TO_INTEGER(index) + 0;  // Add 0 to convert -0 to 0
     // If index is negative, index from the end of the array.
     if (index < 0) {
       index = length + index;
@@ -1409,7 +1409,7 @@ function InnerArrayLastIndexOf(array, element, index, length, argumentsLength) {
   if (argumentsLength < 2) {
     index = length - 1;
   } else {
-    index = TO_INTEGER(index);
+    index = TO_INTEGER(index) + 0;  // Add 0 to convert -0 to 0
     // If index is negative, index from end of the array.
     if (index < 0) index += length;
     // If index is still negative, do not search the array.

test/test262/test262.status

@@ -331,11 +331,6 @@
   'intl402/Collator/prototype/compare/10.3.2_CS_d_NN': [PASS, FAIL_OK],
   'intl402/Date/prototype/13.3.0_7': [PASS, FAIL_OK],
 
-  # Some tests are too strict, checking SameValue rather than ===
-  # https://github.com/tc39/test262/issues/435
-  'built-ins/Array/prototype/indexOf/15.4.4.14-5-9': [FAIL],
-  'built-ins/Array/prototype/lastIndexOf/15.4.4.15-5-9': [FAIL],
-
   # https://github.com/tc39/test262/issues/489
   # Test will pass in 0 or -GMT, but fail in +GMT
   'language/statements/class/subclass/builtin-objects/Date/regular-subclassing': [PASS, FAIL_OK],