Remove old & invalid msie < 9 support code

[wilzbach]

Turns out that DDox's macro processor doesn't insert a newline when newlines occur in macros.
The workaround is to use good, old HTML.

The old MSIE < 9 support code lead to the final "}" being removed.

See also: dlang/ddox#204

[dlang-bot]

Thanks for your pull request, @wilzbach!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	18761	major	Page for assumeUnique documentation displays incorrectly

[wilzbach]

Before:

 $(RUNNABLE_EXAMPLE
 ----
 string letters()
 {
   char[] result = new char['z' - 'a' + 1];
   foreach (i, ref e; result)
   {
     e = cast(char)('a' + i);
   }
   return assumeUnique(result);
 }
 ----
 )

And after rendering the macros:

<div class="runnable-examples"> ----
 string letters()
 {
   char[] result = new char['z' - 'a' + 1];
   foreach (i, ref e; result)
   {
     e = cast(char)('a' + i);
   }
   return assumeUnique(result);
 }
 ----
 </div>

---

After:

$(RUNNABLE_EXAMPLE
 ----
 string letters()
 {
   char[] result = new char['z' - 'a' + 1];
   foreach (i, ref e; result)
   {
     e = cast(char)('a' + i);
   }
   return assumeUnique(result);
 }
 ----
 )

And after rendering the macros:

<div class="runnable-examples">
 ----
 string letters()
 {
   char[] result = new char['z' - 'a' + 1];
   foreach (i, ref e; result)
   {
     e = cast(char)('a' + i);
   }
   return assumeUnique(result);
 }
 ----

</div>