Change the default appearance of buttons, checkboxes, and radio buttons to 'auto'

This doesn't change rendering behavior, but changes
|getComputedStyle(element)['appearance']| results. The new behavior
matches to Firefox.

Bug: 965432
Change-Id: I4ac0e91ebb9abfa5509b4429c62126cdf91a5acf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2462990
Auto-Submit: Kent Tamura <tkent@chromium.org>
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816075}

third_party/blink/renderer/core/html/resources/html.css

@@ -396,7 +396,7 @@ fieldset {
 }
 
 button {
-    -webkit-appearance: button; /* AutoAppearanceFor() should match to this. */
+    appearance: auto;
 }
 
 /* Form controls don't go vertical. */
@@ -601,7 +601,7 @@ input[type="radio" i], input[type="checkbox" i] {
 
 input[type="button" i], input[type="submit" i], input[type="reset" i] {
     -internal-empty-line-height: fabricated;
-    -webkit-appearance: push-button; /* AutoAppearanceFor() should match to this. */
+    appearance: auto;
     -webkit-user-select: none;
     white-space: pre
 }
@@ -711,17 +711,17 @@ param {
 }
 
 input[type="checkbox" i] {
-    -webkit-appearance: checkbox; /* AutoAppearanceFor() should match to this. */
+    appearance: auto;
     box-sizing: border-box;
 }
 
 input[type="radio" i] {
-    -webkit-appearance: radio; /* AutoAppearanceFor() should match to this. */
+    appearance: auto;
     box-sizing: border-box;
 }
 
 input[type="color" i] {
-    -webkit-appearance: square-button; /* AutoAppearanceFor() should match to this. */
+    appearance: auto;
     width: 44px;
     height: 23px;
     background-color: ButtonFace;

third_party/blink/web_tests/external/wpt/html/rendering/widgets/appearance/default-styles-expected.txt

@@ -14,17 +14,17 @@ FAIL <input type="time"> assert_equals: -webkit-appearance expected "auto" but g
 FAIL <input type="datetime-local"> assert_equals: -webkit-appearance expected "auto" but got "textfield"
 FAIL <input type="number"> assert_equals: -webkit-appearance expected "auto" but got "textfield"
 FAIL <input type="range"> assert_equals: -webkit-appearance expected "auto" but got "slider-horizontal"
-FAIL <input type="color"> assert_equals: -webkit-appearance expected "auto" but got "square-button"
-FAIL <input type="checkbox"> assert_equals: -webkit-appearance expected "auto" but got "checkbox"
-FAIL <input type="radio"> assert_equals: -webkit-appearance expected "auto" but got "radio"
-FAIL <input type="submit"> assert_equals: -webkit-appearance expected "auto" but got "push-button"
-FAIL <input type="reset"> assert_equals: -webkit-appearance expected "auto" but got "push-button"
-FAIL <input type="button"> assert_equals: -webkit-appearance expected "auto" but got "push-button"
+PASS <input type="color">
+PASS <input type="checkbox">
+PASS <input type="radio">
+PASS <input type="submit">
+PASS <input type="reset">
+PASS <input type="button">
 FAIL <input type="unknowntype"> assert_equals: -webkit-appearance expected "auto" but got "textfield"
 FAIL <select> assert_equals: -webkit-appearance expected "auto" but got "menulist"
 FAIL <select multiple=""> assert_equals: -webkit-appearance expected "auto" but got "listbox"
 FAIL <select size="2"> assert_equals: -webkit-appearance expected "auto" but got "listbox"
-FAIL <button> assert_equals: -webkit-appearance expected "auto" but got "button"
+PASS <button>
 FAIL <textarea> assert_equals: -webkit-appearance expected "auto" but got "textarea"
 PASS <meter>
 PASS <progress>