Add script to remove prefixed CSS from third_party/polymer.

third_party/polymer/v1_0/components-chromium/iron-flex-layout/iron-flex-layout.html

Index: third_party/polymer/v1_0/components-chromium/iron-flex-layout/iron-flex-layout.html
diff --git a/third_party/polymer/v1_0/components-chromium/iron-flex-layout/iron-flex-layout.html b/third_party/polymer/v1_0/components-chromium/iron-flex-layout/iron-flex-layout.html
index d98e9d0fddf06b7ca3d1f69b8f50321bd078a559..66714bb9f3b7abb500078f3c76dae1249705ab6a 100644
--- a/third_party/polymer/v1_0/components-chromium/iron-flex-layout/iron-flex-layout.html
+++ b/third_party/polymer/v1_0/components-chromium/iron-flex-layout/iron-flex-layout.html
@@ -57,202 +57,139 @@ A complete [guide](https://elements.polymer-project.org/guides/flex-layout) to `
   :root {
 
     --layout: {
-      display: -ms-flexbox;
-      display: -webkit-flex;
       display: flex;
     };
 
     --layout-inline: {
-      display: -ms-inline-flexbox;
-      display: -webkit-inline-flex;
       display: inline-flex;
     };
 
     --layout-horizontal: {
       @apply(--layout);
 
-      -ms-flex-direction: row;
-      -webkit-flex-direction: row;
       flex-direction: row;
     };
 
     --layout-horizontal-reverse: {
       @apply(--layout);
 
-      -ms-flex-direction: row-reverse;
-      -webkit-flex-direction: row-reverse;
       flex-direction: row-reverse;
     };
 
     --layout-vertical: {
       @apply(--layout);
 
-      -ms-flex-direction: column;
-      -webkit-flex-direction: column;
       flex-direction: column;
     };
 
     --layout-vertical-reverse: {
       @apply(--layout);
 
-      -ms-flex-direction: column-reverse;
-      -webkit-flex-direction: column-reverse;
       flex-direction: column-reverse;
     };
 
     --layout-wrap: {
-      -ms-flex-wrap: wrap;
-      -webkit-flex-wrap: wrap;
       flex-wrap: wrap;
     };
 
     --layout-wrap-reverse: {
-      -ms-flex-wrap: wrap-reverse;
-      -webkit-flex-wrap: wrap-reverse;
       flex-wrap: wrap-reverse;
     };
 
     --layout-flex-auto: {
-      -ms-flex: 1 1 auto;
-      -webkit-flex: 1 1 auto;
       flex: 1 1 auto;
     };
 
     --layout-flex-none: {
-      -ms-flex: none;
-      -webkit-flex: none;
       flex: none;
     };
 
     --layout-flex: {
-      -ms-flex: 1 1 0.000000001px;
-      -webkit-flex: 1;
       flex: 1;
-      -webkit-flex-basis: 0.000000001px;
       flex-basis: 0.000000001px;
     };
 
     --layout-flex-2: {
-      -ms-flex: 2;
-      -webkit-flex: 2;
       flex: 2;
     };
 
     --layout-flex-3: {
-      -ms-flex: 3;
-      -webkit-flex: 3;
       flex: 3;
     };
 
     --layout-flex-4: {
-      -ms-flex: 4;
-      -webkit-flex: 4;
       flex: 4;
     };
 
     --layout-flex-5: {
-      -ms-flex: 5;
-      -webkit-flex: 5;
       flex: 5;
     };
 
     --layout-flex-6: {
-      -ms-flex: 6;
-      -webkit-flex: 6;
       flex: 6;
     };
 
     --layout-flex-7: {
-      -ms-flex: 7;
-      -webkit-flex: 7;
       flex: 7;
     };
 
     --layout-flex-8: {
-      -ms-flex: 8;
-      -webkit-flex: 8;
       flex: 8;
     };
 
     --layout-flex-9: {
-      -ms-flex: 9;
-      -webkit-flex: 9;
       flex: 9;
     };
 
     --layout-flex-10: {
-      -ms-flex: 10;
-      -webkit-flex: 10;
       flex: 10;
     };
 
     --layout-flex-11: {
-      -ms-flex: 11;
-      -webkit-flex: 11;
       flex: 11;
     };
 
     --layout-flex-12: {
-      -ms-flex: 12;
-      -webkit-flex: 12;
       flex: 12;
     };
 
     /* alignment in cross axis */
 
     --layout-start: {
-      -ms-flex-align: start;
-      -webkit-align-items: flex-start;
       align-items: flex-start;
     };
 
     --layout-center: {
-      -ms-flex-align: center;
-      -webkit-align-items: center;
       align-items: center;
     };
 
     --layout-end: {
-      -ms-flex-align: end;
-      -webkit-align-items: flex-end;
       align-items: flex-end;
     };
 
     --layout-baseline: {
-      -ms-flex-align: baseline;
-      -webkit-align-items: baseline;
       align-items: baseline;
     };
 
     /* alignment in main axis */
 
     --layout-start-justified: {
-      -ms-flex-pack: start;
-      -webkit-justify-content: flex-start;
       justify-content: flex-start;
     };
 
     --layout-center-justified: {
-      -ms-flex-pack: center;
-      -webkit-justify-content: center;
       justify-content: center;
     };
 
     --layout-end-justified: {
-      -ms-flex-pack: end;
-      -webkit-justify-content: flex-end;
       justify-content: flex-end;
     };
 
     --layout-around-justified: {
-      -ms-flex-pack: distribute;
-      -webkit-justify-content: space-around;
       justify-content: space-around;
     };
 
     --layout-justified: {
-      -ms-flex-pack: justify;
-      -webkit-justify-content: space-between;
       justify-content: space-between;
     };
 
@@ -264,69 +201,44 @@ A complete [guide](https://elements.polymer-project.org/guides/flex-layout) to `
     /* self alignment */
 
     --layout-self-start: {
-      -ms-align-self: flex-start;
-      -webkit-align-self: flex-start;
       align-self: flex-start;
     };
 
     --layout-self-center: {
-      -ms-align-self: center;
-      -webkit-align-self: center;
       align-self: center;
     };
 
     --layout-self-end: {
-      -ms-align-self: flex-end;
-      -webkit-align-self: flex-end;
       align-self: flex-end;
     };
 
     --layout-self-stretch: {
-      -ms-align-self: stretch;
-      -webkit-align-self: stretch;
       align-self: stretch;
     };
 
     --layout-self-baseline: {
-      -ms-align-self: baseline;
-      -webkit-align-self: baseline;
       align-self: baseline;
     };
 
     /* multi-line alignment in main axis */
 
     --layout-start-aligned: {
-      -ms-flex-line-pack: start;  /* IE10 */
-      -ms-align-content: flex-start;
-      -webkit-align-content: flex-start;
       align-content: flex-start;
     };
 
     --layout-end-aligned: {
-      -ms-flex-line-pack: end;  /* IE10 */
-      -ms-align-content: flex-end;
-      -webkit-align-content: flex-end;
       align-content: flex-end;
     };
 
     --layout-center-aligned: {
-      -ms-flex-line-pack: center;  /* IE10 */
-      -ms-align-content: center;
-      -webkit-align-content: center;
       align-content: center;
     };
 
     --layout-between-aligned: {
-      -ms-flex-line-pack: justify;  /* IE10 */
-      -ms-align-content: space-between;
-      -webkit-align-content: space-between;
       align-content: space-between;
     };
 
     --layout-around-aligned: {
-      -ms-flex-line-pack: distribute;  /* IE10 */
-      -ms-align-content: space-around;
-      -webkit-align-content: space-around;
       align-content: space-around;
     };