Generify DefaultWorkbenchBrowserSupport

And switch from Hashtable to Map to reduce useless synchronizatoin.

Signed-off-by: Alexander Kurtakov <akurtako@redhat.com>

Change-Id: I87d1a1bfc522e03f396db2d8edf65c58b7fb22a6
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.ui/+/191697
Tested-by: Platform Bot <platform-bot@eclipse.org>
Reviewed-by: Alexander Kurtakov <akurtako@redhat.com>
diff --git a/bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/browser/DefaultWorkbenchBrowserSupport.java b/bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/browser/DefaultWorkbenchBrowserSupport.java
index 45c9a79..a9eed56 100644
--- a/bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/browser/DefaultWorkbenchBrowserSupport.java
+++ b/bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/browser/DefaultWorkbenchBrowserSupport.java
@@ -13,7 +13,8 @@
  *******************************************************************************/
 package org.eclipse.ui.internal.browser;
 
-import java.util.Hashtable;
+import java.util.HashMap;
+import java.util.Map;
 import org.eclipse.ui.PartInitException;
 import org.eclipse.ui.browser.AbstractWorkbenchBrowserSupport;
 import org.eclipse.ui.browser.IWebBrowser;
@@ -29,14 +30,14 @@
  * @since 3.1
  */
 public class DefaultWorkbenchBrowserSupport extends AbstractWorkbenchBrowserSupport {
-	private Hashtable browsers;
+	private Map<String, IWebBrowser> browsers;
 	private static final String DEFAULT_BROWSER_ID_BASE = "org.eclipse.ui.defaultBrowser"; //$NON-NLS-1$
 
 	/**
 	 * The default constructor.
 	 */
 	public DefaultWorkbenchBrowserSupport() {
-		browsers = new Hashtable();
+		browsers = new HashMap<>();
 	}
 
 	void registerBrowser(IWebBrowser browser) {
@@ -48,7 +49,7 @@
 	}
 
 	IWebBrowser findBrowser(String id) {
-		return (IWebBrowser) browsers.get(id);
+		return browsers.get(id);
 	}
 
 	protected IWebBrowser doCreateBrowser(int style, String browserId, String name, String tooltip)