Output precompiled snapshot size.

runtime/vm/snapshot.h

Index: runtime/vm/snapshot.h
diff --git a/runtime/vm/snapshot.h b/runtime/vm/snapshot.h
index a95e28ebfda858656a1198facbae1f70d4c7f27e..51cf5caa98e56d4630f7f0701c4ea3b37f3f296f 100644
--- a/runtime/vm/snapshot.h
+++ b/runtime/vm/snapshot.h
@@ -804,14 +804,17 @@ class InstructionsWriter : public ZoneAllocated {
                      intptr_t initial_size)
     : stream_(buffer, alloc, initial_size),
       next_offset_(InstructionsSnapshot::kHeaderSize),
+      binary_size_(0),
       instructions_() {
     ASSERT(buffer != NULL);
     ASSERT(alloc != NULL);
   }
 
-  // Size of the snapshot.
+  // Size of the snapshot (assembly code).
   intptr_t BytesWritten() const { return stream_.bytes_written(); }
 
+  intptr_t binary_size() { return binary_size_; }
+
   int32_t GetOffsetFor(RawInstructions* instructions);
 
   void SetInstructionsCode(RawInstructions* insns, RawCode* code) {
@@ -848,10 +851,12 @@ class InstructionsWriter : public ZoneAllocated {
 #else
     stream_.Print(".long 0x%0.8" Px "\n", value);
 #endif
+    binary_size_ += sizeof(value);
   }
 
   WriteStream stream_;
   intptr_t next_offset_;
+  intptr_t binary_size_;
   GrowableArray<InstructionsData> instructions_;
 
   DISALLOW_COPY_AND_ASSIGN(InstructionsWriter);