IDL compiler: remove redundant '_name' from template parameters

'_name' is redundant in template parameter names (it's just string
substitution), so this removes it, primarily simplifying:
{{cpp_class_name}} => {{cpp_class}}
{{v8_class_name}} => {{v8_class}}
This helps readability a lot, as these are really common.
(Discussed previously.)

BUG=239771
NOTRY=true
TBR=haraken

Review URL: https://codereview.chromium.org/101443002

git-svn-id: svn://svn.chromium.org/blink/trunk@163073 bbb929c8-8fbe-4397-9dbb-9b2b20218538