title: Crash when doing scrollToLocation on SectionList
body: <p>We have an edge case in our app. After the UI is rendered and the user tries to scroll to a section it throws <code>scrolltoindex should be used in conjunction with getitemlayout or on scrolltoindex failed</code>. Now this happens only when he does this immediately after UI render. </p>
  
  <pre><code>_scrollToSection = index =&gt; {
      setTimeout(() =&gt; {
          this.list.scrollToLocation({
              animated: true,
              itemIndex: -1,
              sectionIndex: index,
              viewPosition: 0
          });
      }, 150);
  };
  </code></pre>
  
  <p>Section list render:</p>
  
  <pre><code>        &lt;SectionList
              sections={this.props.sections}
              extraData={this.props.subscriber}
              ref={ref =&gt; {
                  if (ref) {
                      this.list = ref;
                  }
              }}
              automaticallyAdjustContentInsets={true}
              contentInsetAdjustmentBehavior={'automatic'}
              windowSize={100}
              ListHeaderComponent={this.props.header || null}
              ItemSeparatorComponent={() =&gt; (
                  &lt;Separator
                      style={[mediumStyle.separatorEnd, { backgroundColor: IOS_GREY_02_03 }]}
                  /&gt;
              )}
              renderSectionFooter={() =&gt; &lt;View style={{ height: 17 }} /&gt;}
              keyExtractor={(item, index) =&gt; index}
              removeClippedSubviews={false}
              stickySectionHeadersEnabled={true}
              renderSectionHeader={({ section }) =&gt; (
                  &lt;SectionTitle title={section.title} theme={this.props.theme} /&gt;
              )}
              renderItem={this._renderItem}
              onEndReachedThreshold={0}
              onEndReached={() =&gt; HapticFeedback.trigger()}
              scrollEventThrottle={16}
          /&gt;
  </code></pre>
  
  <p>I tried to google the cause but was unsuccessful finding only outdated and  closed issues without a solution. Did this happen to anybody else? How did you fixed it? </p>
  
  <p><strong>UPDATE:</strong>
  We have come up on a solution of constant item sizes which also takes in count the accessibility scale factor. So we had an item and header size we could use in <code>getItemLayout</code>. All worked as should, but the <code>SectionList</code> is glitchy. When we scrolled to lower sections, the list was jumpy by itself without any interaction. 
  So far the best solution we had was to build the section list ourselves in native code and use that instead of the RN list.</p>