Fix issue where dropdown position is incorrect with page scroll gr-textarea did not take into account scroll position when positioning the emoji dropdown. This fixes it by adding scrollTop to non-fixed position textareas. Change-Id: I490d03443b4ca910602ab0636f3dfc19957fdd89

diff --git a/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea.js b/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea.js
index 955f75d..9158a57 100644
--- a/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea.js
+++ b/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea.js

@@ -206,6 +206,10 @@
           10);
     },
 
+    _getScrollTop() {
+      return document.body.scrollTop;
+    },
+
     /**
      * This positions the dropdown to be just below the cursor position. It is
      * calculated by having a hidden element with the same width and styling of
@@ -219,7 +223,12 @@
       const caratPosition = this._getPositionOfCursor();
       const fontSize = this._getFontSize();
 
-      const top = caratPosition.top + fontSize + VERTICAL_OFFSET + 'px';
+      let top = caratPosition.top + fontSize + VERTICAL_OFFSET;
+
+      if (!this.fixedPositionDropdown) {
+        top += this._getScrollTop();
+      }
+      top += 'px';
       const left = caratPosition.left + 'px';
       this.$.emojiSuggestions.setPosition(top, left);
     },

diff --git a/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea_test.html b/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea_test.html
index c92a479..1c5dea3 100644
--- a/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea_test.html
+++ b/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea_test.html

@@ -181,9 +181,12 @@
       sandbox.stub(element, '_getPositionOfCursor', () => {
         return {top: 100, left: 30};
       });
-      sandbox.stub(element, '_getFontSize', () => {
-        return 12;
-      });
+      sandbox.stub(element, '_getFontSize', () => 12);
+      sandbox.stub(element, '_getScrollTop', () => 100);
+      element._updateSelectorPosition();
+      assert.isTrue(setPositionSpy.lastCall.calledWithExactly('219px', '30px'));
+
+      element.fixedPositionDropdown = true;
       element._updateSelectorPosition();
       assert.isTrue(setPositionSpy.lastCall.calledWithExactly('119px', '30px'));
     });