[WebView] Reduce focus scope for text input.

Previous implementation treated input method state as the
indicator for changing focus state. This leads to overlapping
scope and lifetime issues. This changelist ties the lifetime to
the actual providing a narrower scope that's covered by more
events.

Test: Built and tested on web input.
Change-Id: Ica13234861aecc7f365df1b7d39411ba321b2768
diff --git a/Source/WebKit/fuchsia/WebCoreSupport/WebEditorClient.cpp b/Source/WebKit/fuchsia/WebCoreSupport/WebEditorClient.cpp
index 507fbbe..6015e8c 100644
--- a/Source/WebKit/fuchsia/WebCoreSupport/WebEditorClient.cpp
+++ b/Source/WebKit/fuchsia/WebCoreSupport/WebEditorClient.cpp
@@ -299,12 +299,12 @@
 
 void WebEditorClient::textFieldDidBeginEditing(Element* element)
 {
-    notImplemented();
+    m_inputFocusDelegate(true);
 }
 
 void WebEditorClient::textFieldDidEndEditing(Element* element)
 {
-    notImplemented();
+    m_inputFocusDelegate(false);
 }
 
 void WebEditorClient::textDidChangeInTextField(Element* element)
@@ -415,7 +415,7 @@
 
 void WebEditorClient::setInputMethodState(bool enabled)
 {
-    m_inputFocusDelegate(enabled);
+    notImplemented();
 }
 
 bool WebEditorClient::supportsGlobalSelection()