Disable web page and object memory cache

Pages and assets should not be retrieved from the cache. This leads to
unexpected results in testing. Also, the raw content of cached objects
and pages cannot be retrieved.

spec/driver_spec.rb

@@ -2070,6 +2070,24 @@ describe Capybara::Webkit::Driver do
     end
   end
 
+  context "caching app" do
+    let(:driver) do
+      etag_value = SecureRandom.hex
+
+      driver_for_app do
+        get '/' do
+          etag etag_value
+        end
+      end
+    end
+
+    it "does not cache responses" do
+      visit '/'
+      visit '/'
+      expect(driver.status_code).to eq(200)
+    end
+  end
+
   context "offline application cache" do
     let(:driver) do
       @visited = []

src/WebPageManager.cpp

@@ -29,6 +29,10 @@ WebPageManager::WebPageManager(QObject *parent) : QObject(parent) {
   m_networkAccessManager =
     new NetworkAccessManager(m_blacklistedRequestHandler, this);
   m_networkAccessManager->setCookieJar(m_cookieJar);
+
+  QWebSettings::setMaximumPagesInCache(0);
+  QWebSettings::setObjectCacheCapacities(0, 0, 0);
+
   createPage()->setFocus();
 }