wasm: Fix compilation failures when not using precompiled headers

Various headers files were missing includes. Compilation only worked
because precompiled headers were used.

Pick-to: 6.5
Change-Id: Ic1b434da53f89d4b4207a22bf171bd966db856ac
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>
(cherry picked from commit 1126a590f92b2642d52d51787c4bee8866f1b685)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/plugins/platforms/wasm/qwasmaccessibility.h

@@ -4,6 +4,9 @@
 #ifndef QWASMACCESIBILITY_H
 #define QWASMACCESIBILITY_H
 
+#include <QtCore/qtconfigmacros.h>
+#include <QtGui/qtguiglobal.h>
+
 #if QT_CONFIG(accessibility)
 
 #include <QtCore/qhash.h>

src/plugins/platforms/wasm/qwasmbase64iconstore.h

@@ -4,6 +4,7 @@
 #ifndef QWASMBASE64IMAGESTORE_H
 #define QWASMBASE64IMAGESTORE_H
 
+#include <string>
 #include <string_view>
 
 #include <QtCore/qtconfigmacros.h>

src/plugins/platforms/wasm/qwasmdom.h

@@ -5,6 +5,7 @@
 #define QWASMDOM_H
 
 #include <QtCore/qtconfigmacros.h>
+#include <QtCore/QPointF>
 
 #include <emscripten/val.h>
 

src/plugins/platforms/wasm/qwasmwindowclientarea.h

@@ -6,6 +6,7 @@
 
 #include <QtCore/qnamespace.h>
 #include <qpa/qwindowsysteminterface.h>
+#include <QtCore/QMap>
 
 #include <emscripten/val.h>