Make Observatory analyzer clean

runtime/observatory/lib/src/elements/cpu_profile.dart

Index: runtime/observatory/lib/src/elements/cpu_profile.dart
diff --git a/runtime/observatory/lib/src/elements/cpu_profile.dart b/runtime/observatory/lib/src/elements/cpu_profile.dart
index 8696b4cc82d217ca18cf77607b04046531f8bd20..bb5a6269d48332e9f7d6245bfabf83e9e63d995f 100644
--- a/runtime/observatory/lib/src/elements/cpu_profile.dart
+++ b/runtime/observatory/lib/src/elements/cpu_profile.dart
@@ -563,10 +563,12 @@ class CpuProfileElement extends ObservatoryElement {
 
   attached() {
     super.attached();
-    sampleBufferControlElement = shadowRoot.query('#sampleBufferControl');
+    sampleBufferControlElement =
+        shadowRoot.querySelector('#sampleBufferControl');
     assert(sampleBufferControlElement != null);
     sampleBufferControlElement.onSampleBufferUpdate = onSampleBufferChange;
-    stackTraceTreeConfigElement = shadowRoot.query('#stackTraceTreeConfig');
+    stackTraceTreeConfigElement =
+        shadowRoot.querySelector('#stackTraceTreeConfig');
     assert(stackTraceTreeConfigElement != null);
     stackTraceTreeConfigElement.onTreeConfigChange = onTreeConfigChange;
     cpuProfileTreeElement = shadowRoot.querySelector('#cpuProfileTree');
@@ -769,13 +771,15 @@ class CpuProfileTableElement extends ObservatoryElement {
 
   attached() {
     super.attached();
-    sampleBufferControlElement = shadowRoot.query('#sampleBufferControl');
+    sampleBufferControlElement =
+        shadowRoot.querySelector('#sampleBufferControl');
     assert(sampleBufferControlElement != null);
     sampleBufferControlElement.onSampleBufferUpdate = onSampleBufferChange;
     // Disable the tag selector- we always want no tags.
     sampleBufferControlElement.tagSelector = 'None';
     sampleBufferControlElement.showTagSelector = false;
-    stackTraceTreeConfigElement = shadowRoot.query('#stackTraceTreeConfig');
+    stackTraceTreeConfigElement =
+        shadowRoot.querySelector('#stackTraceTreeConfig');
     assert(stackTraceTreeConfigElement != null);
     stackTraceTreeConfigElement.onTreeConfigChange = onTreeConfigChange;
     stackTraceTreeConfigElement.modeSelector = 'Function';