Revert "Bug 426021: [StyledText] setAlwaysShowScrollBars(true) not implemented"

This reverts commit f37a5e25493f6c2d77b39affb5d8de583639fa5f (except for the Javadoc change, which was OK).
diff --git a/bundles/org.eclipse.swt/Eclipse SWT Custom Widgets/common/org/eclipse/swt/custom/StyledText.java b/bundles/org.eclipse.swt/Eclipse SWT Custom Widgets/common/org/eclipse/swt/custom/StyledText.java
index 7b88b6e..4982ffe 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT Custom Widgets/common/org/eclipse/swt/custom/StyledText.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT Custom Widgets/common/org/eclipse/swt/custom/StyledText.java
@@ -9434,13 +9434,9 @@
 	ScrollBar horizontalBar = getHorizontalBar();
 	int oldHeight = clientAreaHeight;
 	int oldWidth = clientAreaWidth;
-	if (verticalBar != null) {
-		verticalBar.setVisible(alwaysShowScroll);
-		if (alwaysShowScroll) verticalBar.setValues(0, 0, 0, 1, 1, 1);
-	}
-	if (horizontalBar != null) {
-		horizontalBar.setVisible(alwaysShowScroll);
-		if (alwaysShowScroll) horizontalBar.setValues(0, 0, 0, 1, 1, 1);
+	if (!alwaysShowScroll) {
+		if (verticalBar != null) verticalBar.setVisible(false);
+		if (horizontalBar != null) horizontalBar.setVisible(false);
 	}
 	if (verticalBar != null) {
 		setScrollBar(verticalBar, clientAreaHeight, renderer.getHeight(), topMargin + bottomMargin);