-Fixed deserializing certain Microsoft formated dates

Src/Newtonsoft.Json.Tests/Serialization/JsonSerializerTest.cs

@@ -198,6 +198,18 @@ namespace Newtonsoft.Json.Tests.Serialization
         }
 #endif
 
+#if !NET20
+        [Test]
+        public void DeserializeMSDateTimeOffset()
+        {
+            DateTimeOffset d = JsonConvert.DeserializeObject<DateTimeOffset>(@"""/Date(1418924498000+0800)/""");
+            long initialTicks = DateTimeUtils.ConvertDateTimeToJavaScriptTicks(d.DateTime, d.Offset);
+
+            Assert.AreEqual(1418924498000, initialTicks);
+            Assert.AreEqual(8, d.Offset.Hours);
+        }
+#endif
+
         [Test]
         public void CaseInsensitiveRequiredPropertyConstructorCreation()
         {

Src/Newtonsoft.Json.Tests/Utilities/DateTimeUtilsTests.cs

@@ -177,6 +177,21 @@ namespace Newtonsoft.Json.Tests.Utilities
         }
 
 #if !NET20
+        [Test]
+        public void ReadOffsetMSDateTimeOffset()
+        {
+            char[] c = @"12345/Date(1418924498000+0800)/12345".ToCharArray();
+            StringReference reference = new StringReference(c, 5, c.Length - 10);
+
+            DateTimeOffset d;
+            DateTimeUtils.TryParseDateTimeOffset(reference, null, CultureInfo.InvariantCulture, out d);
+
+            long initialTicks = DateTimeUtils.ConvertDateTimeToJavaScriptTicks(d.DateTime, d.Offset);
+
+            Assert.AreEqual(1418924498000, initialTicks);
+            Assert.AreEqual(8, d.Offset.Hours);
+        }
+
         [Test]
         public void NewDateTimeOffsetParse()
         {

Src/Newtonsoft.Json/JsonWriter.cs

@@ -1286,7 +1286,9 @@ namespace Newtonsoft.Json
                 // this is here because adding a WriteValue(BigInteger) to JsonWriter will
                 // mean the user has to add a reference to System.Numerics.dll
                 if (value is BigInteger)
+                {
                     throw CreateUnsupportedTypeException(this, value);
+                }
 #endif
 
                 WriteValue(this, ConvertUtils.GetTypeCode(value.GetType()), value);

Src/Newtonsoft.Json/Utilities/DateTimeUtils.cs

@@ -482,7 +482,7 @@ namespace Newtonsoft.Json.Utilities
             {
                 kind = DateTimeKind.Local;
 
-                if (!TryReadOffset(text, index, out offset))
+                if (!TryReadOffset(text, index + text.StartIndex, out offset))
                 {
                     ticks = 0;
                     return false;
@@ -494,7 +494,7 @@ namespace Newtonsoft.Json.Utilities
                 index = text.Length - 2;
             }
 
-            return (ConvertUtils.Int64TryParse(text.Chars, 6, index - 6, out ticks) == ParseResult.Success);
+            return (ConvertUtils.Int64TryParse(text.Chars, 6 + text.StartIndex, index - 6, out ticks) == ParseResult.Success);
         }
 
         private static bool TryParseDateTimeMicrosoft(StringReference text, DateTimeZoneHandling dateTimeZoneHandling, out DateTime dt)