RFR: JDK-8288671: Problematic fix for font boosting

[Hannes Wallnöfer]

Please review an important CSS-only fix for the output generated by JavaDoc. 

Various mobile browsers have a feature called "font boosting" or "text 
inflation" to selectively increase the font size of parts of the page to make 
them easier to read. Since javadoc-generated pages have a `<meta 
name="viewport" content="width=device-width, initial-scale=1">` declaration 
that is not really needed, but especially Chrome on Android is very stubborn 
and insists on changing font sizes in an unpredictable way. 

It seems like the only way to prevent Chrome/Android from doing this is to 
include a `min-height` CSS property. In JDK-8277420 we therefore included the 
CSS declaration shown below to avoid headers from changing font size when the 
copy-to-clipboard button is shown:


/* Disable font boosting */
h1, h2, h3, h4, h5, h6 {
    max-height: 2em;
} 


The idea was that a max-height of `2em` would be enough for how headers are 
displayed in our docs, but of course I didn't consider wrapped headers. In 
fact, the main header of the index page is often wrapped twice on small 
browsers/devices, resulting in the header overlapping with the first paragraph:

![Screenshot_20220620-171055~2](https://urldefense.com/v3/__https://user-images.githubusercontent.com/15975/174652966-c7815d9f-1b2f-407c-b241-f11c91e0eca6.png__;!!ACWV5N9M2RV99hQ!L9bYZ7V1_R2dV_M8R9tpM1rfjP1h5qGi_cgGD2BZUDFuJcz9GtOM-aD82gLqiPxrg_IU-JrBKmaudzf02WjYWrg$
 )

Font boosting also occurs in member signatures where some parts are displayed 
with bigger fonts than others. This is less obvious than the other cases, but 
it should also be fixed:

![Screenshot_20220620-104706~2](https://urldefense.com/v3/__https://user-images.githubusercontent.com/15975/174653488-c22f30c8-086f-4533-86f0-43100dee155d.png__;!!ACWV5N9M2RV99hQ!L9bYZ7V1_R2dV_M8R9tpM1rfjP1h5qGi_cgGD2BZUDFuJcz9GtOM-aD82gLqiPxrg_IU-JrBKmaudzf0eKxLBsg$
 )

The proposed fix is to use a very high `max-height` value that is far beyond 
actual height values, and to include member signatures in the CSS selector.

This fixes the problems in the screenshots above in Chrome/Android as shown in 
the screenshots below. It does not have any effects in other browsers.
 
![Screenshot_20220620-171105~2](https://urldefense.com/v3/__https://user-images.githubusercontent.com/15975/174655060-19575a49-2b2c-40cd-ad36-f181f275b2bb.png__;!!ACWV5N9M2RV99hQ!L9bYZ7V1_R2dV_M8R9tpM1rfjP1h5qGi_cgGD2BZUDFuJcz9GtOM-aD82gLqiPxrg_IU-JrBKmaudzf0gjNTxzg$
 )
Fixed index page

![Screenshot_20220620-104658~2](https://urldefense.com/v3/__https://user-images.githubusercontent.com/15975/174655086-5c18dbf6-bd82-43be-bb07-b187f2b89c82.png__;!!ACWV5N9M2RV99hQ!L9bYZ7V1_R2dV_M8R9tpM1rfjP1h5qGi_cgGD2BZUDFuJcz9GtOM-aD82gLqiPxrg_IU-JrBKmaudzf0Rx5WEfg$
 )
Fixed member signature

-------------

Commit messages:
 - JDK-8288671: Problematic fix for font boosting

Changes: https://git.openjdk.org/jdk19/pull/48/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk19&pr=48&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288671
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk19/pull/48.diff
  Fetch: git fetch https://git.openjdk.org/jdk19 pull/48/head:pull/48

PR: https://git.openjdk.org/jdk19/pull/48