Bug 1683226 - part 2: Make `HTMLEmbedElement` and `HTMLObjectElement` stop overriding `nsIContent::GetDesiredIMEState()` r=smaug

Currently, they are never focusable when its type is "plugin".
So, making stop them returning `IMEEnabled::Plugin` won't change
anything, but it guarantees that nobody will see `IMEEnabled::Plugin`
at runtime.  This is a preparation for the following patches.

Differential Revision: https://phabricator.services.mozilla.com/D100101

dom/base/nsObjectLoadingContent.cpp

@@ -1805,20 +1805,7 @@ nsObjectLoadingContent::UpdateObjectParameters() {
   if (newType != mType) {
     retval = (ParameterUpdateFlags)(retval | eParamStateChanged);
     LOG(("OBJLC [%p]: Type changed from %u -> %u", this, mType, newType));
-    bool updateIMEState = (mType == eType_Loading && newType == eType_Plugin);
     mType = newType;
-    // The IME manager needs to know if this is a plugin so it can adjust
-    // input handling to an appropriate mode for plugins.
-    nsFocusManager* fm = nsFocusManager::GetFocusManager();
-    nsCOMPtr<nsIContent> thisContent =
-        do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
-    MOZ_ASSERT(thisContent, "should have content");
-    if (updateIMEState && thisContent && fm && fm->IsFocused(thisContent)) {
-      widget::IMEState state;
-      state.mEnabled = widget::IMEEnabled::Plugin;
-      state.mOpen = widget::IMEState::DONT_CHANGE_OPEN_STATE;
-      IMEStateManager::UpdateIMEState(state, thisContent, nullptr);
-    }
   }
 
   if (!URIEquals(mBaseURI, newBaseURI)) {

dom/html/HTMLEmbedElement.cpp

@@ -186,14 +186,6 @@ bool HTMLEmbedElement::IsHTMLFocusable(bool aWithMouse, bool* aIsFocusable,
   return true;
 }
 
-nsIContent::IMEState HTMLEmbedElement::GetDesiredIMEState() {
-  if (Type() == eType_Plugin) {
-    return IMEState(IMEEnabled::Plugin);
-  }
-
-  return nsGenericHTMLElement::GetDesiredIMEState();
-}
-
 bool HTMLEmbedElement::ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
                                       const nsAString& aValue,
                                       nsIPrincipal* aMaybeScriptedPrincipal,

dom/html/HTMLEmbedElement.h

@@ -46,7 +46,6 @@ class HTMLEmbedElement final : public nsGenericHTMLElement,
 
   virtual bool IsHTMLFocusable(bool aWithMouse, bool* aIsFocusable,
                                int32_t* aTabIndex) override;
-  virtual IMEState GetDesiredIMEState() override;
 
   virtual bool ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
                               const nsAString& aValue,

dom/html/HTMLObjectElement.cpp

@@ -337,14 +337,6 @@ bool HTMLObjectElement::IsHTMLFocusable(bool aWithMouse, bool* aIsFocusable,
   return false;
 }
 
-nsIContent::IMEState HTMLObjectElement::GetDesiredIMEState() {
-  if (Type() == eType_Plugin) {
-    return IMEState(IMEEnabled::Plugin);
-  }
-
-  return nsGenericHTMLFormElement::GetDesiredIMEState();
-}
-
 NS_IMETHODIMP
 HTMLObjectElement::Reset() { return NS_OK; }
 

dom/html/HTMLObjectElement.h

@@ -57,7 +57,6 @@ class HTMLObjectElement final : public nsGenericHTMLFormElement,
 
   virtual bool IsHTMLFocusable(bool aWithMouse, bool* aIsFocusable,
                                int32_t* aTabIndex) override;
-  virtual IMEState GetDesiredIMEState() override;
 
   // Overriden nsIFormControl methods
   NS_IMETHOD Reset() override;

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -975,12 +975,6 @@ interface nsIDOMWindowUtils : nsISupports {
    */
   const unsigned long IME_STATUS_PASSWORD = 2;
 
-  /**
-   * PLUGIN means a plug-in has focus. At this time we should not touch to
-   * controlling the IME state.
-   */
-  const unsigned long IME_STATUS_PLUGIN   = 3;
-
   /**
    * Get IME status, see above IME_STATUS_* definitions.
    */

widget/tests/test_imestate.html

@@ -663,12 +663,6 @@ function runPluginTest() {
     return;
   }
 
-  if (navigator.platform.indexOf("Mac") == 0) {
-    // XXX on mac, currently, this test isn't passed because it doesn't return
-    // IME_STATUS_PLUGIN by its bug.
-    return;
-  }
-
   var plugin = document.getElementById("plugin");
 
   // Plugins are not supported and their elements should not accept focus;