Canged CodedInputStream.ReadTag to use boolean result with out params to
support reading a field name rather than a field tag.
diff --git a/src/ProtocolBuffers.Test/TestProtos/UnitTestMessageSetProtoFile.cs b/src/ProtocolBuffers.Test/TestProtos/UnitTestMessageSetProtoFile.cs
index 89bf459..5e5cea7 100644
--- a/src/ProtocolBuffers.Test/TestProtos/UnitTestMessageSetProtoFile.cs
+++ b/src/ProtocolBuffers.Test/TestProtos/UnitTestMessageSetProtoFile.cs
@@ -255,7 +255,7 @@
         while (input.ReadTag(out tag, out field_name)) {

           switch (tag) {

             case 0: {

-              throw InvalidProtocolBufferException.InvalidTag();

+              throw pb::InvalidProtocolBufferException.InvalidTag();

             }

             default: {

               if (pb::WireFormat.IsEndGroupTag(tag)) {

@@ -457,7 +457,7 @@
         while (input.ReadTag(out tag, out field_name)) {

           switch (tag) {

             case 0: {

-              throw InvalidProtocolBufferException.InvalidTag();

+              throw pb::InvalidProtocolBufferException.InvalidTag();

             }

             default: {

               if (pb::WireFormat.IsEndGroupTag(tag)) {

@@ -706,7 +706,7 @@
         while (input.ReadTag(out tag, out field_name)) {

           switch (tag) {

             case 0: {

-              throw InvalidProtocolBufferException.InvalidTag();

+              throw pb::InvalidProtocolBufferException.InvalidTag();

             }

             default: {

               if (pb::WireFormat.IsEndGroupTag(tag)) {

@@ -932,7 +932,7 @@
         while (input.ReadTag(out tag, out field_name)) {

           switch (tag) {

             case 0: {

-              throw InvalidProtocolBufferException.InvalidTag();

+              throw pb::InvalidProtocolBufferException.InvalidTag();

             }

             default: {

               if (pb::WireFormat.IsEndGroupTag(tag)) {

@@ -1208,7 +1208,7 @@
             while (input.ReadTag(out tag, out field_name)) {

               switch (tag) {

                 case 0: {

-                  throw InvalidProtocolBufferException.InvalidTag();

+                  throw pb::InvalidProtocolBufferException.InvalidTag();

                 }

                 default: {

                   if (pb::WireFormat.IsEndGroupTag(tag)) {

@@ -1436,7 +1436,7 @@
         while (input.ReadTag(out tag, out field_name)) {

           switch (tag) {

             case 0: {

-              throw InvalidProtocolBufferException.InvalidTag();

+              throw pb::InvalidProtocolBufferException.InvalidTag();

             }

             default: {

               if (pb::WireFormat.IsEndGroupTag(tag)) {