Add --parse-all option in order to benchmark and measure the scanner/parser performance.

runtime/vm/compiler.h

Index: runtime/vm/compiler.h
diff --git a/runtime/vm/compiler.h b/runtime/vm/compiler.h
index 1e8e3fc5be880b296ed01b1162daca8c9edc28c4..4ec478f19a8b2da515175af10cbdbe7cf8d447c6 100644
--- a/runtime/vm/compiler.h
+++ b/runtime/vm/compiler.h
@@ -100,6 +100,7 @@ class Compiler : public AllStatic {
   //
   // Returns Error::null() if there is no compilation error.
   static RawError* CompileFunction(Thread* thread, const Function& function);
+  static RawError* ParseFunction(Thread* thread, const Function& function);
 
   // Generates unoptimized code if not present, current code is unchanged.
   static RawError* EnsureUnoptimizedCode(Thread* thread,
@@ -143,6 +144,7 @@ class Compiler : public AllStatic {
   //
   // Returns Error::null() if there is no compilation error.
   static RawError* CompileAllFunctions(const Class& cls);
+  static RawError* ParseAllFunctions(const Class& cls);
 
   // Notify the compiler that background (optimized) compilation has failed
   // because the mutator thread changed the state (e.g., deoptimization,