remove empty css flags tags (#32150)

removed from:
css/css-writing-modes
css/css-text
css/css-flexbox
css/css-display

Author: DanielRyanSmith

css/css-display/run-in/after-content-display-004.xht

@@ -11,7 +11,6 @@
   <link rel="help" href="http://www.w3.org/TR/CSS21/generate.html#before-after-content" title="12.1 The :before and :after pseudo-elements" />
   <link rel="help" href="http://www.w3.org/TR/css3-box/#run-in-boxes" title="4.3. Run-in boxes" />
 
-  <meta content="" name="flags" />
   <meta content="Generated content can have their own display value explicitly set in which case they behave as if they were real elements inserted just inside their associated element." name="assert" />
 
   <style type="text/css"><![CDATA[

css/css-display/run-in/anonymous-box-generation-002.xht

@@ -4,7 +4,6 @@
         <title>CSS Test: Anonymous run-in box generation</title>
         <link rel="author" title="Microsoft" href="http://www.microsoft.com/" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/visuren.html#anonymous-block-level" />
-        <meta name="flags" content="" />
         <meta name="assert" content="Block boxes with inline content followed by a run-in box generate an anonymous run-in box around the inline content." />
         <style type="text/css">
             div

css/css-display/run-in/background-applies-to-011.xht

@@ -5,7 +5,6 @@
         <link rel="author" title="Microsoft" href="http://www.microsoft.com/" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/colors.html#propdef-background" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/colors.html#background-properties" />
-        <meta name="flags" content="" />
         <meta name="assert" content="The 'background' property applies to elements with 'display' set to 'run-in'." />
         <style type="text/css">
             div

css/css-display/run-in/background-color-applies-to-011.xht

@@ -5,7 +5,6 @@
         <link rel="author" title="Microsoft" href="http://www.microsoft.com/" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/colors.html#propdef-background-color" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/colors.html#background-properties" />
-        <meta name="flags" content="" />
         <meta name="assert" content="The 'background-color' property applies to elements with 'display' set to 'run-in'." />
         <style type="text/css">
             div

css/css-display/run-in/before-content-display-004.xht

@@ -11,7 +11,6 @@
   <link rel="help" href="http://www.w3.org/TR/CSS21/generate.html#before-after-content" title="12.1 The :before and :after pseudo-elements" />
   <link rel="help" href="http://www.w3.org/TR/css3-box/#run-in-boxes" title="4.3. Run-in boxes" />
 
-  <meta content="" name="flags" />
   <meta content="Generated content can have their own display value explicitly set in which case they behave as if they were real elements inserted just inside their associated element." name="assert" />
 
   <style type="text/css"><![CDATA[

css/css-display/run-in/border-applies-to-011.xht

@@ -5,7 +5,6 @@
         <link rel="author" title="Microsoft" href="http://www.microsoft.com/" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/box.html#propdef-border" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/box.html#border-shorthand-properties" />
-        <meta name="flags" content="" />
         <meta name="assert" content="The 'border' property applies to elements with a display of run-in." />
         <style type="text/css">
             div

css/css-display/run-in/border-bottom-applies-to-011.xht

@@ -5,7 +5,6 @@
         <link rel="author" title="Microsoft" href="http://www.microsoft.com/" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/box.html#propdef-border-bottom" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/box.html#border-shorthand-properties" />
-        <meta name="flags" content="" />
         <meta name="assert" content="The 'border-bottom' property applies to elements with a display of run-in." />
         <style type="text/css">
             div

css/css-display/run-in/border-bottom-color-applies-to-011.xht

@@ -5,7 +5,6 @@
         <link rel="author" title="Microsoft" href="http://www.microsoft.com/" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/box.html#propdef-border-bottom-color" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/box.html#border-color-properties" />
-        <meta name="flags" content="" />
         <meta name="assert" content="The 'border-bottom-color' property applies to elements with a display of run-in." />
         <style type="text/css">
             div

css/css-display/run-in/border-bottom-style-applies-to-011.xht

@@ -5,7 +5,6 @@
         <link rel="author" title="Microsoft" href="http://www.microsoft.com/" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/box.html#propdef-border-bottom-style" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/box.html#border-style-properties" />
-        <meta name="flags" content="" />
         <meta name="assert" content="The 'border-bottom-style' property applies to elements with a display of run-in." />
         <style type="text/css">
             div

css/css-display/run-in/border-bottom-width-applies-to-011.xht

@@ -5,7 +5,6 @@
         <link rel="author" title="Microsoft" href="http://www.microsoft.com/" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/box.html#propdef-border-bottom-width" />
         <link rel="help" href="http://www.w3.org/TR/CSS21/box.html#border-width-properties" />
-        <meta name="flags" content="" />
         <meta name="assert" content="The 'border-bottom-width' property applies to elements with a display of run-in." />
         <style type="text/css">
             div