Support locking of directory entries

Moves the locking algorithm from file entry to file system entry.

Fixes whatwg#137

Author: Nathan Memmott

index.bs

@@ -559,7 +559,7 @@ The <dfn method for=FileSystemFileHandle>getFile()</dfn> method steps are:
      the temporary file starts out empty,
      otherwise the existing file is first copied to this temporary file.
 
-     Creating a {{FileSystemWritableFileStream}} [=file system entry/lock/take a lock|takes a shared lock=] on the
+     Creating a {{FileSystemWritableFileStream}} [=file system entry/take a lock|takes a shared lock=] on the
      [=file entry=] [=locate an entry|locatable=] with |fileHandle|'s [=FileSystemHandle/locator=].
      This prevents the creation of {{FileSystemSyncAccessHandle|FileSystemSyncAccessHandles}}
      for the entry, until the stream is closed.
@@ -596,7 +596,7 @@ The <dfn method for=FileSystemFileHandle>createWritable(|options|)</dfn> method
      |result| with a "{{NotFoundError}}" {{DOMException}} and abort these steps.
   1. [=Assert=]: |entry| is a [=file entry=].
 
-  1. Let |lockResult| be the result of [=file system entry/lock/take a lock|taking a lock=]
+  1. Let |lockResult| be the result of [=file system entry/take a lock|taking a lock=]
      with "`shared`" on |entry|.
 
   1. [=Queue a storage task=] with |global| to run these steps:
@@ -624,7 +624,7 @@ The <dfn method for=FileSystemFileHandle>createWritable(|options|)</dfn> method
      [=file entry=] [=locate an entry|locatable=] by |fileHandle|'s [=FileSystemHandle/locator=].
      To ensure the changes are reflected in this file, the handle can be flushed.
 
-     Creating a {{FileSystemSyncAccessHandle}} [=file system entry/lock/take a lock|takes an exclusive lock=] on the
+     Creating a {{FileSystemSyncAccessHandle}} [=file system entry/take a lock|takes an exclusive lock=] on the
      [=file entry=] [=locate an entry|locatable=] with |fileHandle|'s [=FileSystemHandle/locator=].
      This prevents the creation of further {{FileSystemSyncAccessHandle|FileSystemSyncAccessHandles}}
      or {{FileSystemWritableFileStream|FileSystemWritableFileStreams}}
@@ -666,7 +666,7 @@ The <dfn method for=FileSystemFileHandle>createSyncAccessHandle()</dfn> method s
      |result| with a "{{NotFoundError}}" {{DOMException}} and abort these steps.
   1. [=Assert=]: |entry| is a [=file entry=].
 
-  1. Let |lockResult| be the result of [=file system entry/lock/take a lock|taking a lock=]
+  1. Let |lockResult| be the result of [=file system entry/take a lock|taking a lock=]
      with "`exclusive`" on |entry|.
 
   1. [=Queue a storage task=] with |global| to run these steps: