Add a trace event for ResourceFetcher::requestResource

This could help better understand the Blink resource-fetching overhead
seen, for example, in XMLHttpRequest.send().

R=japhet@chromium.org
BUG=348655

Review URL: https://codereview.chromium.org/213353003

git-svn-id: svn://svn.chromium.org/blink/trunk@170676 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Apply the correct style to first-letter pseudo elements composed of different renderers

Traverse (in preorder) the whole subtree under a render block with a first-letter selector when
looking for the text renderers which would need to get the apropriate style applied, instead of
only considering the first renderer only, which might not contain all the text that should be
considered as a "first letter" (leading and trailing punctuation should be included too).

The present patch also considers leading spaces, if any, as part of the first-letter element,
to match the behaviour of other renderers such as IE and Opera (Firefox does not do that).

R=eae@chromium.org, leviw@chromium.org
BUG=354403
TEST=Add new test to check first-letter elements composed of different renderers.

Review URL: https://codereview.chromium.org/207553007

git-svn-id: svn://svn.chromium.org/blink/trunk@170677 bbb929c8-8fbe-4397-9dbb-9b2b20218538