rustdoc-search: remove parallel searchWords array

This might have made sense if the algorithm could use `searchWords`
to skip having to look at `searchIndex`, but since it always
does a substring check on both the stock word and the normalizedName,
it doesn't seem to help performance anyway.

tests/rustdoc-js/substring.js

@@ -1,7 +1,15 @@
-const EXPECTED = {
-    'query': 'waker_from',
-    'others': [
-        { 'path': 'substring::SuperWaker', 'name': 'local_waker_from_nonlocal' },
-        { 'path': 'substring::SuperWakerTask', 'name': 'local_waker_from_nonlocal' },
-    ],
-};
+const EXPECTED = [
+    {
+        'query': 'waker_from',
+        'others': [
+            { 'path': 'substring::SuperWaker', 'name': 'local_waker_from_nonlocal' },
+            { 'path': 'substring::SuperWakerTask', 'name': 'local_waker_from_nonlocal' },
+        ],
+    },
+    {
+        'query': 'my',
+        'others': [
+            { 'path': 'substring', 'name': 'm_y_substringmatching' },
+        ],
+    },
+];

tests/rustdoc-js/substring.rs

@@ -19,3 +19,5 @@ impl SuperWakerTask {
     pub fn waker_non_local() {}
     pub fn from_non_local() {}
 }
+
+pub fn m_y_substringmatching() {}