Fix build (by outlining static double constant).

runtime/vm/object.cc

Index: runtime/vm/object.cc
===================================================================
--- runtime/vm/object.cc	(revision 38294)
+++ runtime/vm/object.cc	(working copy)
@@ -7745,7 +7745,7 @@
   }
 
   static const intptr_t kInitialTableSize = 32;
-  static const double kMaxLoadFactor = 0.75;
+  static const double kMaxLoadFactor;
 
   uint8_t* buffer_;
   WriteStream stream_;
@@ -7755,6 +7755,9 @@
 };
 
 
+const double CompressedTokenStreamData::kMaxLoadFactor = 0.75;
+
+
 RawTokenStream* TokenStream::New(const Scanner::GrowableTokenStream& tokens,
                                  const String& private_key) {
   // Copy the relevant data out of the scanner into a compressed stream of