Always mark stdout as blocking when using 'print'.

runtime/bin/platform_android.cc

Index: runtime/bin/platform_android.cc
diff --git a/runtime/bin/platform_android.cc b/runtime/bin/platform_android.cc
index dfa2e27ac82cd2dc1ce231e11972883afe687386..445ea014dcc88ce9659335be2ef920d3dc02895b 100644
--- a/runtime/bin/platform_android.cc
+++ b/runtime/bin/platform_android.cc
@@ -11,6 +11,8 @@
 #include <string.h>  // NOLINT
 #include <unistd.h>  // NOLINT
 
+#include "bin/fdutils.h"
+
 
 namespace dart {
 namespace bin {
@@ -64,6 +66,18 @@ void Platform::FreeEnvironment(char** env, intptr_t count) {
   delete[] env;
 }
 
+
+void Platform::PrintBlocking(FILE* file, const char* format, ...) {
+  int fd = fileno(file);
+  FDUtils::SetBlocking(fd);
+  va_list args;
+  va_start(args, format);
+  vfprintf(file, format, args);
+  fflush(file);
+  va_end(args);
+  FDUtils::SetNonBlocking(fd);
+}
+
 }  // namespace bin
 }  // namespace dart