--- old/modules/web/src/main/native/Source/WTF/wtf/DateMath.cpp	2016-01-13 11:54:35.835573520 +0530
+++ new/modules/web/src/main/native/Source/WTF/wtf/DateMath.cpp	2016-01-13 11:54:35.735573519 +0530
@@ -523,12 +523,10 @@
 
 static inline double ymdhmsToSeconds(int year, long mon, long day, long hour, long minute, double second)
 {
-    double days = (day - 32075)
-        + floor(1461 * (year + 4800.0 + (mon - 14) / 12) / 4)
-        + 367 * (mon - 2 - (mon - 14) / 12 * 12) / 12
-        - floor(3 * ((year + 4900.0 + (mon - 14) / 12) / 100) / 4)
-        - 2440588;
-    return ((days * hoursPerDay + hour) * minutesPerHour + minute) * secondsPerMinute + second;
+    int mday = firstDayOfMonth[isLeapYear(year)][mon - 1];
+    double ydays = daysFrom1970ToYear(year);
+
+    return (second + minute * secondsPerMinute + hour * secondsPerHour + (mday + day - 1 + ydays) * secondsPerDay);
 }
 
 // We follow the recommendation of RFC 2822 to consider all
--- old/modules/web/src/test/java/test/javafx/scene/web/MiscellaneousTest.java	2016-01-13 11:54:36.155573524 +0530
+++ new/modules/web/src/test/java/test/javafx/scene/web/MiscellaneousTest.java	2016-01-13 11:54:36.035573523 +0530
@@ -103,12 +103,26 @@
     @Test public void testRT26306() {
         loadContent(
                 "<script language='javascript'>\n" +
-                "var s = '0123456789abcdef';\n" +
-                "while (true) {\n" +
-                "    alert(s.length);\n" +
-                "    s = s + s;\n" +
-                "}\n" +
-                "</script>");
+                        "var s = '0123456789abcdef';\n" +
+                        "while (true) {\n" +
+                        "    alert(s.length);\n" +
+                        "    s = s + s;\n" +
+                        "}\n" +
+                        "</script>");
+    }
+
+    @Test public void testJavaScriptDateParser() {
+        // JDK-8146898 : Date object parsing failure
+        submit(() -> {
+            String dateFromString = (String) getEngine().
+                    executeScript("(new Date('December 31, 2034 23:59:59')).toUTCString()");
+
+            String dateFromInt = (String) getEngine().
+                    executeScript("(new Date(2034, 11, 31, 23, 59, 59)).toUTCString()");
+
+            assertEquals("JavaScript Date object parsing from String and Integer",
+                    true, dateFromString.equalsIgnoreCase(dateFromInt));
+        });
     }
 
     private WebEngine createWebEngine() {