Reduce memory use immediately after boot.

test/cctest/test-mark-compact.cc

Index: test/cctest/test-mark-compact.cc
===================================================================
--- test/cctest/test-mark-compact.cc	(revision 10555)
+++ test/cctest/test-mark-compact.cc	(working copy)
@@ -534,15 +534,15 @@
     intptr_t booted_memory = MemoryInUse();
     if (sizeof(initial_memory) == 8) {
       if (v8::internal::Snapshot::IsEnabled()) {
-        CHECK_LE(booted_memory - initial_memory, 6654 * 1024);  // 6444.
+        CHECK_LE(booted_memory - initial_memory, 3050 * 1024);  // 2984.
       } else {
-        CHECK_LE(booted_memory - initial_memory, 6777 * 1024);  // 6596.
+        CHECK_LE(booted_memory - initial_memory, 3050 * 1024);  // 3008.
       }
     } else {
       if (v8::internal::Snapshot::IsEnabled()) {
-        CHECK_LE(booted_memory - initial_memory, 6500 * 1024);  // 6356.
+        CHECK_LE(booted_memory - initial_memory, 2000 * 1024);  // 1940.
       } else {
-        CHECK_LE(booted_memory - initial_memory, 6654 * 1024);  // 6424
+        CHECK_LE(booted_memory - initial_memory, 2000 * 1024);  // 1948
       }
     }
   }