Update test for distinct NaN replacement on DefineOwnProperty

Fixes gh-683
Ref gh-648
Ref tc39/ecma262#353

test/built-ins/Object/internals/DefineOwnProperty/nan-equivalence.js

@@ -4,9 +4,16 @@
 esid: sec-ordinary-object-internal-methods-and-internal-slots-defineownproperty-p-desc
 es6id: 9.1.6
 description: >
-  Compares "value" field using SameValue algorithm (thereby ignoring distinct
-  NaN values)
+  Replaces value field even if they pass in the SameValue algorithm, including
+  distinct NaN values
 info: |
+  Previously, this method compared the "value" field using the SameValue
+  algorithm (thereby ignoring distinct NaN values)
+
+  ---
+
+  [[DefineOwnProperty]] (P, Desc)
+
   1. Return ? OrdinaryDefineOwnProperty(O, P, Desc).
 
   9.1.6.1 OrdinaryDefineOwnProperty
@@ -19,9 +26,17 @@ info: |
   9.1.6.3 ValidateAndApplyPropertyDescriptor
 
   [...]
-  4. Return true, if every field in Desc also occurs in current and the value
-     of every field in Desc is the same value as the corresponding field in
-     current when compared using the SameValue algorithm.
+  7. Else if IsDataDescriptor(current) and IsDataDescriptor(Desc) are both true,
+     then
+    a. If the [[Configurable]] field of current is false, then
+      [...]
+    b. Else the [[Configurable]] field of current is true, so any change is
+       acceptable.
+  [...]
+  9. If O is not undefined, then
+    a. For each field of Desc that is present, set the corresponding attribute
+       of the property named P of object O to the value of the field.
+  10. Return true.
 features: [Float64Array, Uint8Array]
 includes: [nans.js]
 ---*/
@@ -39,7 +54,7 @@ function byteValue(value) {
 /**
  * Iterate over each pair of distinct NaN values (with replacement). If two or
  * more suitable NaN values cannot be identified, the semantics under test
- * cannot be verfied and this test is expected to pass without evaluating any
+ * cannot be verified and this test is expected to pass without evaluating any
  * assertions.
  */
 for (idx = 0; idx < length; ++idx) {
@@ -54,10 +69,10 @@ for (idx = 0; idx < length; ++idx) {
     subject.prop = first;
     subject.prop = second;
 
-    assert.notSameValue(
+    assert.sameValue(
       byteValue(subject.prop),
       byteValue(second),
-      'Property value was not re-set'
+      'Property value was re-set'
     );
   }
 }