[api] Remove deprecated PropertyDescriptor constructor

The implicit constructor is deprecated since version 7.3, hence can be
removed in 7.4.

R=ulan@chromium.org

Change-Id: I54a530240648c1721924195d7fccc157d483e6d8
Reviewed-on: https://chromium-review.googlesource.com/c/1436018Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59116}

include/v8.h

@@ -4188,14 +4188,6 @@ class V8_EXPORT PropertyDescriptor {
   // GenericDescriptor
   PropertyDescriptor();
 
-  // DataDescriptor (implicit / DEPRECATED)
-  // Templatized such that the explicit constructor is chosen first.
-  // TODO(clemensh): Remove after 7.3 branch.
-  template <std::nullptr_t = nullptr>
-  V8_DEPRECATED(
-      "Use explicit constructor",
-      PropertyDescriptor(Local<Value> value));  // NOLINT(runtime/explicit)
-
   // DataDescriptor
   explicit PropertyDescriptor(Local<Value> value);
 
@@ -4236,11 +4228,6 @@ class V8_EXPORT PropertyDescriptor {
   PrivateData* private_;
 };
 
-// TODO(clemensh): Remove after 7.3 branch.
-template <std::nullptr_t>
-PropertyDescriptor::PropertyDescriptor(Local<Value> value)
-    : PropertyDescriptor(value) {}
-
 /**
  * An instance of the built-in Proxy constructor (ECMA-262, 6th Edition,
  * 26.2.1).