Bug 1735098 - Implement EpochTimeStamp from HR-Time r=edgar

Add the EpochTimeStamp, which can be used to incrementally rename/remove DOMTimeStamp. See also https://github.com/w3c/hr-time/pull/124 and https://github.com/whatwg/webidl/pull/1021

Differential Revision: https://phabricator.services.mozilla.com/D128030

dom/bindings/parser/WebIDL.py

@@ -8668,7 +8668,6 @@ class Parser(Tokenizer):
 
     # Builtin IDL defined by WebIDL
     _builtins = """
-        typedef unsigned long long DOMTimeStamp;
         typedef (ArrayBufferView or ArrayBuffer) BufferSource;
     """
 

dom/imptests/idlharness.js

@@ -416,6 +416,7 @@ IdlArray.prototype.assert_type_is = function(value, type)
             return;
 
         case "unsigned long long":
+        case "EpochTimeStamp":
         case "DOMTimeStamp":
             assert_equals(typeof value, "number");
             assert_true(0 <= value, "unsigned long long is negative");

dom/interfaces/base/domstubs.idl

@@ -11,7 +11,9 @@ class nsWrapperCache;
 
 [ptr] native nsWrapperCachePtr(nsWrapperCache);
 
+// DOMTimeStamp is deprecated, use EpochTimeStamp instead.
 typedef unsigned long long DOMTimeStamp;
+typedef unsigned long long EpochTimeStamp;
 typedef double DOMHighResTimeStamp;
 typedef unsigned long long nsViewID;
 

dom/webidl/Performance.webidl

@@ -14,6 +14,9 @@
  * W3C liability, trademark and document use rules apply.
  */
 
+// DOMTimeStamp is deprecated, use EpochTimeStamp instead.
+typedef unsigned long long DOMTimeStamp;
+typedef unsigned long long EpochTimeStamp;
 typedef double DOMHighResTimeStamp;
 typedef sequence <PerformanceEntry> PerformanceEntryList;