Fraction class prototype and test (not to be committed).

runtime/vm/snapshot.cc

Index: runtime/vm/snapshot.cc
diff --git a/runtime/vm/snapshot.cc b/runtime/vm/snapshot.cc
index 41959955949172ca7d6645626533c034a5227e5f..5baf6f4749594d1433893215a76a9d42eeff9d26 100644
--- a/runtime/vm/snapshot.cc
+++ b/runtime/vm/snapshot.cc
@@ -354,6 +354,7 @@ void SnapshotReader::SetReadException(const char* msg) {
   result = DartLibraryCalls::InstanceCreate(library,
                                             Symbols::ArgumentError(),
                                             Symbols::Dot(),
+                                            false,  // Not a factory.
                                             args);
   const Stacktrace& stacktrace = Stacktrace::Handle(zone());
   const UnhandledException& error = UnhandledException::Handle(
@@ -890,7 +891,7 @@ RawTypedData* SnapshotReader::NewTypedData(intptr_t class_id, intptr_t len) {
 
 
 #define ALLOC_NEW_OBJECT(type)                                                 \
-  ASSERT(Snapshot::IsFull(kind_));                                            \
+  ASSERT(Snapshot::IsFull(kind_));                                             \
   ASSERT_NO_SAFEPOINT_SCOPE();                                                 \
   return reinterpret_cast<Raw##type*>(                                         \
       AllocateUninitialized(k##type##Cid, type::InstanceSize()));              \
@@ -901,6 +902,11 @@ RawBigint* SnapshotReader::NewBigint() {
 }
 
 
+RawFraction* SnapshotReader::NewFraction() {
+  ALLOC_NEW_OBJECT(Fraction);
+}
+
+
 RawUnresolvedClass* SnapshotReader::NewUnresolvedClass() {
   ALLOC_NEW_OBJECT(UnresolvedClass);
 }
@@ -1696,6 +1702,7 @@ uword SnapshotWriter::GetObjectTags(RawObject* raw) {
   V(Mint)                                                                      \
   V(Bigint)                                                                    \
   V(Double)                                                                    \
+  V(Fraction)                                                                  \
   V(ImmutableArray)                                                            \
 
 #define VM_OBJECT_WRITE(clazz)                                                 \