Meta "keywords" tag malformed in overview-summary.html and related pages

The recent change to simplify the text on the javadoc API overview page
has had some bad side-effects.

This is the changeset:
http://hg.openjdk.java.net/jdk9/dev/rev/7df4f16bfa8f

And these are some of the changed lines:

-JDK_SHORT_NAME := JDK™ $(VERSION_SPECIFICATION)
-JDK_LONG_NAME := Standard Edition Development Kit (JDK™) $(VERSION_SPECIFICATION)
+JDK_SHORT_NAME := Java SE $(VERSION_SPECIFICATION) & JDK $(VERSION_SPECIFICATION)
+JDK_LONG_NAME := Java^® Platform, Standard Edition \
+ <span style="white-space: nowrap;">&amp; Java Development Kit</span>

- $1_HEADER_TITLE := <strong>$$(JAVA_PLATFORM)<br>$$($1_SHORT_NAME)</strong> \
- $$(DRAFT_MARKER_STR)
+ ifeq ($(VERSION_IS_GA), true) # Workaround stylesheet bug
+ $1_HEADER_PAD := 14
+ else
+ $1_HEADER_PAD := 9
+ endif
+ $1_HEADER_TITLE := <div style="margin-top: $$($1_HEADER_PAD)px;"><strong>$$($1_SHORT_NAME)</strong> \
+ $$(DRAFT_MARKER_STR)</div>

Now look at how they're showing up in some of the HTML pages:

<meta name="keywords" content="Overview List,
Java&lt;sup&gt;&amp;reg;&lt;/sup&gt; Platform, Standard Edition &lt;span
style="white-space: nowrap;"&gt;&amp;amp; Java Development
Kit&lt;/span&gt;&lt;br&gt;Version 9 API Specification">

If it were just encoding the HTML, that would be ugly but acceptable.
What's worse is that it is /not/ encoding the string quotes, meaning the
strings are resolved as follows (if you can see colored text)

<meta name="keywords" content="Overview List,
Java&lt;sup&gt;&amp;reg;&lt;/sup&gt; Platform, Standard Edition &lt;span
style="white-space: nowrap;"&gt;&amp;amp; Java Development
Kit&lt;/span&gt;&lt;br&gt;Version 9 API Specification">

And that is causing the tidy program to report errors such as the following:

$ tidy -e
/w/jjg/work/dev/build/linux-x86_64-normal-server-release/images/docs/api/jdk.charsets-frame.html
line 8 column 1 - Warning: <meta> attribute "nowrap;"&gt;&amp;amp;"
lacks value
line 8 column 1 - Warning: <meta> attribute
"kit&lt;/span&gt;&lt;br&gt;version" lacks value
line 8 column 1 - Warning: <meta> attribute "9" lacks value
line 8 column 1 - Warning: <meta> attribute with missing trailing quote mark
line 21 column 84 - Warning: <div> isn't allowed in <h1> elements
line 21 column 1 - Info: <h1> previously mentioned
line 21 column 206 - Warning: discarding unexpected </div>
line 8 column 1 - Warning: <meta> proprietary attribute "white-space:"
line 8 column 1 - Warning: <meta> proprietary attribute "java"
line 8 column 1 - Warning: <meta> proprietary attribute "development"
line 8 column 1 - Warning: <meta> proprietary attribute "api"
Info: Document content looks like HTML5
Tidy found 10 warnings and 0 errors!