Add a method to convert unsigned C integer into V8 Integer.

src/checks.h

Index: src/checks.h
===================================================================
--- src/checks.h	(revision 3009)
+++ src/checks.h	(working copy)
@@ -80,7 +80,26 @@
   }
 }
 
+// Helper function used by the CHECK_EQ function when given int64_t
+// arguments.  Should not be called directly.
+static inline void CheckEqualsHelper(const char* file, int line,
+                                     const char* expected_source,
+                                     int64_t expected,
+                                     const char* value_source,
+                                     int64_t value) {
+  if (expected != value) {
+    // Sorry, printing int64_t in a fanky hex way,
+    // that's our mother tongue after all :)
+    V8_Fatal(file, line,
+             "CHECK_EQ(%s, %s) failed\n#"
+             "   Expected: 0x%08x%08x\n#   Found: 0x%08x%08x",
+             expected_source, value_source,
+             uint32_t(expected >> 32), uint32_t(expected),
+             uint32_t(value >> 32), uint32_t(value));
+  }
+}
 
+
 // Helper function used by the CHECK_NE function when given int
 // arguments.  Should not be called directly.
 static inline void CheckNonEqualsHelper(const char* file,