MD Settings: more consistently fix error message space for search engine

chrome/browser/resources/settings/search_engines_page/search_engine_dialog.html

Index: chrome/browser/resources/settings/search_engines_page/search_engine_dialog.html
diff --git a/chrome/browser/resources/settings/search_engines_page/search_engine_dialog.html b/chrome/browser/resources/settings/search_engines_page/search_engine_dialog.html
index d749e17ec6c70a1dc7ea391ac59f540859645cb8..b56c87314d717669ae90eac686a7e8d7039f917f 100644
--- a/chrome/browser/resources/settings/search_engines_page/search_engine_dialog.html
+++ b/chrome/browser/resources/settings/search_engines_page/search_engine_dialog.html
@@ -11,6 +11,12 @@
       :host {
         --paper-input-container: {
           /**
+           * Prevent paper-input-container's default padding rule to eat up
+           * our padding-bottom rule.
+           */
+          padding: 8px 0;

[dpapad, 2017/03/31 01:22:18]

Given the complication you discovered, would be it more readable to simply merge
both padding rules to the following?

padding: 8px 0 calc(1rem - 8px) 0;

[scottchen, 2017/03/31 20:35:33]

Done.

+
+          /**
            * Saves space for error message. Using calc to leave just enough
            * space at all font sizes (default 0, grow/shrink with font-size).
            */