Revert of Introduce ModulePendingScript (patchset #6 id:100001 of htt…

…ps://codereview.chromium.org/2815453006/ )

Reason for revert:
Reason for revert:
https://codereview.chromium.org/2653923008/ is
suspected to cause CHECK() failure (crbug.com/711703)
inside PendingScript's prefinalizer.

BUG=711703

Original issue's description:
> Introduce ModulePendingScript
>
> BUG=594639
>
> Review-Url: https://codereview.chromium.org/2815453006
> Cr-Commit-Position: refs/heads/master@{#464627}
> Committed: https://chromium.googlesource.com/chromium/src/+/2e5a5b8efccf655f183cc7ce0c59a88f77bb50f5

TBR=kouhei@chromium.org,yhirano@chromium.org,sigbjornf@opera.com,japhet@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=594639

Review-Url: https://codereview.chromium.org/2816043005
Cr-Commit-Position: refs/heads/master@{#464765}
(cherry picked from commit 80f482b)

Review-Url: https://codereview.chromium.org/2825523002 .
Cr-Commit-Position: refs/branch-heads/3071@{#16}
Cr-Branched-From: a106f0a-refs/heads/master@{#464641}

third_party/WebKit/Source/core/dom/BUILD.gn

@@ -197,8 +197,6 @@ blink_core_sources("dom") {
     "Modulator.h",
     "ModuleMap.cpp",
     "ModuleMap.h",
-    "ModulePendingScript.cpp",
-    "ModulePendingScript.h",
     "ModuleScript.cpp",
     "ModuleScript.h",
     "MutationCallback.h",

third_party/WebKit/Source/core/dom/Modulator.h

@@ -34,13 +34,6 @@ class SingleModuleClient : public GarbageCollectedMixin {
   virtual void NotifyModuleLoadFinished(ModuleScript*) = 0;
 };
 
-// A ModuleTreeClient is notified when a module script and its whole descendent
-// tree load is complete.
-class ModuleTreeClient : public GarbageCollectedMixin {
- public:
-  virtual void NotifyModuleTreeLoadFinished(ModuleScript*) = 0;
-};
-
 // spec: "top-level module fetch flag"
 // https://html.spec.whatwg.org/multipage/webappapis.html#fetching-scripts-is-top-level
 enum class ModuleGraphLevel { kTopLevelModuleFetch, kDependentModuleFetch };