Bug 689288 - xpcshell\tests\js\src\xpconnect\tests\unit\test_attributes.js and test_params.js are perma-orange on Win64. r=bsmedberg

js/src/xpconnect/tests/unit/xpcshell.ini

@@ -22,8 +22,4 @@ fail-if = os == "android"
 [test_xpcomutils.js]
 [test_unload.js]
 [test_attributes.js]
-# Bug 689288
-fail-if = os == "win" && processor == "x86_64"
 [test_params.js]
-# Bug 689288
-fail-if = os == "win" && processor == "x86_64"

xpcom/reflect/xptcall/src/md/win32/xptcstubs_x86_64.cpp

@@ -159,7 +159,10 @@ PrepareAndDispatch(nsXPTCStubBase* self, PRUint32 methodIndex, PRUint64* args,
 
         case nsXPTType::T_FLOAT:
              if (iCount < PARAM_FPR_COUNT)
-                dp->val.f  = (float)fprData[iCount++];
+                // The value in xmm register is already prepared to
+                // be retrieved as a float. Therefore, we pass the
+                // value verbatim, as a double without conversion.
+                dp->val.d  = (double)fprData[iCount++];
              else
                 dp->val.f  = *((float*)ap++);
              break;