Introduce a RandonNumberGenerator class. Refactor the random/private_random uses in Isolate/Context.

src/platform/time.h

Index: src/platform/time.h
diff --git a/src/platform/time.h b/src/platform/time.h
index 3fed6287fe0d1e0b2bdd0b79830285ae9b2da88a..2ce6cdd3e99137505243ca47d139eeab5f7a0e34 100644
--- a/src/platform/time.h
+++ b/src/platform/time.h
@@ -222,6 +222,15 @@ class Time V8_FINAL BASE_EMBEDDED {
   // with which we might compare it.
   static Time Max() { return Time(std::numeric_limits<int64_t>::max()); }
 
+  // Converts to/from internal values. The meaning of the "internal value" is
+  // completely up to the implementation, so it should be treated as opaque.
+  static Time FromInternalValue(int64_t value) {
+    return Time(value);
+  }
+  int64_t ToInternalValue() const {
+    return us_;
+  }
+
   // Converts to/from POSIX time specs.
   static Time FromTimespec(struct timespec ts);
   struct timespec ToTimespec() const;
@@ -329,6 +338,15 @@ class TimeTicks V8_FINAL BASE_EMBEDDED {
   // Returns true if this object has not been initialized.
   bool IsNull() const { return ticks_ == 0; }
 
+  // Converts to/from internal values. The meaning of the "internal value" is
+  // completely up to the implementation, so it should be treated as opaque.
+  static TimeTicks FromInternalValue(int64_t value) {
+    return TimeTicks(value);
+  }
+  int64_t ToInternalValue() const {
+    return ticks_;
+  }
+
   TimeTicks& operator=(const TimeTicks other) {
     ticks_ = other.ticks_;
     return *this;